diff --git a/Grid/Makefile.am b/Grid/Makefile.am
index ded6d146..7c3c151b 100644
--- a/Grid/Makefile.am
+++ b/Grid/Makefile.am
@@ -54,9 +54,11 @@ Version.h: version-cache
 include Make.inc
 include Eigen.inc
 
-extra_sources+=$(ZWILS_FERMION_FILES)
 extra_sources+=$(WILS_FERMION_FILES)
 extra_sources+=$(STAG_FERMION_FILES)
+if BUILD_ZMOBIUS
+  extra_sources+=$(ZWILS_FERMION_FILES)
+endif
 if BUILD_GPARITY
   extra_sources+=$(GP_FERMION_FILES)
 endif
diff --git a/Grid/cartesian/Cartesian_red_black.h b/Grid/cartesian/Cartesian_red_black.h
index b71981f5..092d4910 100644
--- a/Grid/cartesian/Cartesian_red_black.h
+++ b/Grid/cartesian/Cartesian_red_black.h
@@ -36,7 +36,7 @@ static const int CbBlack=1;
 static const int Even   =CbRed;
 static const int Odd    =CbBlack;
 
-accelerator_inline int RedBlackCheckerBoardFromOindex (int oindex, Coordinate &rdim, Coordinate &chk_dim_msk)
+accelerator_inline int RedBlackCheckerBoardFromOindex (int oindex,const Coordinate &rdim,const Coordinate &chk_dim_msk)
 {
   int nd=rdim.size();
   Coordinate coor(nd);
diff --git a/Grid/lattice/Lattice_view.h b/Grid/lattice/Lattice_view.h
index 3b76b921..cb568abd 100644
--- a/Grid/lattice/Lattice_view.h
+++ b/Grid/lattice/Lattice_view.h
@@ -67,9 +67,14 @@ public:
   accelerator_inline const vobj & operator()(size_t i) const { return this->_odata[i]; }
 #endif
 
+#if 1
+  //  accelerator_inline const vobj & operator[](size_t i) const { return this->_odata[i]; };
+  accelerator_inline vobj       & operator[](size_t i) const { return this->_odata[i]; };
+#else
   accelerator_inline const vobj & operator[](size_t i) const { return this->_odata[i]; };
   accelerator_inline vobj       & operator[](size_t i)       { return this->_odata[i]; };
-
+#endif
+  
   accelerator_inline uint64_t begin(void) const { return 0;};
   accelerator_inline uint64_t end(void)   const { return this->_odata_size; };
   accelerator_inline uint64_t size(void)  const { return this->_odata_size; };
diff --git a/Grid/qcd/action/ActionBase.h b/Grid/qcd/action/ActionBase.h
index bff21d1d..17980ee0 100644
--- a/Grid/qcd/action/ActionBase.h
+++ b/Grid/qcd/action/ActionBase.h
@@ -41,7 +41,7 @@ class Action
 public:
   bool is_smeared = false;
   // Heatbath?
-  virtual void refresh(const GaugeField& U, GridParallelRNG& pRNG) = 0; // refresh pseudofermions
+  virtual void refresh(const GaugeField& U, GridSerialRNG &sRNG, GridParallelRNG& pRNG) = 0; // refresh pseudofermions
   virtual RealD S(const GaugeField& U) = 0;                             // evaluate the action
   virtual void deriv(const GaugeField& U, GaugeField& dSdU) = 0;        // evaluate the action derivative
   virtual std::string action_name()    = 0;                             // return the action name
diff --git a/Grid/qcd/action/fermion/FermionOperatorImpl.h b/Grid/qcd/action/fermion/FermionOperatorImpl.h
index b444f6dc..9345c0e6 100644
--- a/Grid/qcd/action/fermion/FermionOperatorImpl.h
+++ b/Grid/qcd/action/fermion/FermionOperatorImpl.h
@@ -153,8 +153,8 @@ public:
   typedef typename Impl::StencilImpl             StencilImpl;		\
   typedef typename Impl::ImplParams               ImplParams;	        \
   typedef typename Impl::StencilImpl::View_type  StencilView;		\
-  typedef typename ViewMap<FermionField>::Type      FermionFieldView;	\
-  typedef typename ViewMap<DoubledGaugeField>::Type DoubledGaugeFieldView;
+  typedef const typename ViewMap<FermionField>::Type      FermionFieldView;	\
+  typedef const typename ViewMap<DoubledGaugeField>::Type DoubledGaugeFieldView;
 
 #define INHERIT_IMPL_TYPES(Base)		\
   INHERIT_GIMPL_TYPES(Base)			\
diff --git a/Grid/qcd/action/fermion/WilsonCompressor.h b/Grid/qcd/action/fermion/WilsonCompressor.h
index 10e98f33..0760bcba 100644
--- a/Grid/qcd/action/fermion/WilsonCompressor.h
+++ b/Grid/qcd/action/fermion/WilsonCompressor.h
@@ -61,7 +61,7 @@ public:
   typedef typename SiteHalfSpinor::vector_type     vComplexHigh;
   constexpr static int Nw=sizeof(SiteHalfSpinor)/sizeof(vComplexHigh);
 
-  accelerator_inline int CommDatumSize(void) {
+  accelerator_inline int CommDatumSize(void) const {
     return sizeof(SiteHalfCommSpinor);
   }
 
@@ -69,7 +69,7 @@ public:
   /* Compress includes precision change if mpi data is not same */
   /*****************************************************/
   template<class _SiteHalfSpinor, class _SiteSpinor>
-  accelerator_inline void Compress(_SiteHalfSpinor *buf,Integer o,const _SiteSpinor &in) {
+  accelerator_inline void Compress(_SiteHalfSpinor *buf,Integer o,const _SiteSpinor &in) const {
     _SiteHalfSpinor tmp;
     projector::Proj(tmp,in,mu,dag);
     vstream(buf[o],tmp);
@@ -81,7 +81,7 @@ public:
   accelerator_inline void Exchange(SiteHalfSpinor *mp,
 				   const SiteHalfSpinor * __restrict__ vp0,
 				   const SiteHalfSpinor * __restrict__ vp1,
-				   Integer type,Integer o){
+				   Integer type,Integer o) const {
     SiteHalfSpinor tmp1;
     SiteHalfSpinor tmp2;
     exchange(tmp1,tmp2,vp0[o],vp1[o],type);
@@ -93,7 +93,7 @@ public:
   /* Have a decompression step if mpi data is not same */
   /*****************************************************/
   accelerator_inline void Decompress(SiteHalfSpinor * __restrict__ out,
-				     SiteHalfSpinor * __restrict__ in, Integer o) {    
+				     SiteHalfSpinor * __restrict__ in, Integer o) const {    
     assert(0);
   }
 
@@ -103,7 +103,7 @@ public:
   accelerator_inline void CompressExchange(SiteHalfSpinor * __restrict__ out0,
 					   SiteHalfSpinor * __restrict__ out1,
 					   const SiteSpinor * __restrict__ in,
-					   Integer j,Integer k, Integer m,Integer type)
+					   Integer j,Integer k, Integer m,Integer type) const
   {
     SiteHalfSpinor temp1, temp2;
     SiteHalfSpinor temp3, temp4;
@@ -117,7 +117,7 @@ public:
   /*****************************************************/
   /* Pass the info to the stencil */
   /*****************************************************/
-  accelerator_inline bool DecompressionStep(void) { return false; }
+  accelerator_inline bool DecompressionStep(void) const { return false; }
 
 };
 
@@ -142,7 +142,7 @@ public:
   typedef typename SiteHalfSpinor::vector_type     vComplexHigh;
   constexpr static int Nw=sizeof(SiteHalfSpinor)/sizeof(vComplexHigh);
 
-  accelerator_inline int CommDatumSize(void) {
+  accelerator_inline int CommDatumSize(void) const {
     return sizeof(SiteHalfCommSpinor);
   }
 
@@ -150,7 +150,7 @@ public:
   /* Compress includes precision change if mpi data is not same */
   /*****************************************************/
   template<class _SiteHalfSpinor, class _SiteSpinor>
-  accelerator_inline void Compress(_SiteHalfSpinor *buf,Integer o,const _SiteSpinor &in) {
+  accelerator_inline void Compress(_SiteHalfSpinor *buf,Integer o,const _SiteSpinor &in) const {
     _SiteHalfSpinor hsp;
     SiteHalfCommSpinor *hbuf = (SiteHalfCommSpinor *)buf;
     projector::Proj(hsp,in,mu,dag);
@@ -163,7 +163,7 @@ public:
   accelerator_inline void Exchange(SiteHalfSpinor *mp,
                        SiteHalfSpinor *vp0,
                        SiteHalfSpinor *vp1,
-		       Integer type,Integer o){
+		       Integer type,Integer o) const {
     SiteHalfSpinor vt0,vt1;
     SiteHalfCommSpinor *vpp0 = (SiteHalfCommSpinor *)vp0;
     SiteHalfCommSpinor *vpp1 = (SiteHalfCommSpinor *)vp1;
@@ -175,7 +175,7 @@ public:
   /*****************************************************/
   /* Have a decompression step if mpi data is not same */
   /*****************************************************/
-  accelerator_inline void Decompress(SiteHalfSpinor *out, SiteHalfSpinor *in, Integer o){
+  accelerator_inline void Decompress(SiteHalfSpinor *out, SiteHalfSpinor *in, Integer o) const {
     SiteHalfCommSpinor *hin=(SiteHalfCommSpinor *)in;
     precisionChange((vComplexHigh *)&out[o],(vComplexLow *)&hin[o],Nw);
   }
@@ -186,7 +186,7 @@ public:
   accelerator_inline void CompressExchange(SiteHalfSpinor *out0,
 			       SiteHalfSpinor *out1,
 			       const SiteSpinor *in,
-			       Integer j,Integer k, Integer m,Integer type){
+			       Integer j,Integer k, Integer m,Integer type) const {
     SiteHalfSpinor temp1, temp2,temp3,temp4;
     SiteHalfCommSpinor *hout0 = (SiteHalfCommSpinor *)out0;
     SiteHalfCommSpinor *hout1 = (SiteHalfCommSpinor *)out1;
@@ -200,7 +200,7 @@ public:
   /*****************************************************/
   /* Pass the info to the stencil */
   /*****************************************************/
-  accelerator_inline bool DecompressionStep(void) { return true; }
+  accelerator_inline bool DecompressionStep(void) const { return true; }
 
 };
 
diff --git a/Grid/qcd/action/fermion/WilsonImpl.h b/Grid/qcd/action/fermion/WilsonImpl.h
index d7941d1f..94676b6b 100644
--- a/Grid/qcd/action/fermion/WilsonImpl.h
+++ b/Grid/qcd/action/fermion/WilsonImpl.h
@@ -72,7 +72,7 @@ public:
   typedef WilsonCompressor<SiteHalfCommSpinor,SiteHalfSpinor, SiteSpinor> Compressor;
   typedef WilsonImplParams ImplParams;
   typedef WilsonStencil<SiteSpinor, SiteHalfSpinor,ImplParams> StencilImpl;
-  typedef typename StencilImpl::View_type StencilView;
+  typedef const typename StencilImpl::View_type StencilView;
     
   ImplParams Params;
 
diff --git a/Grid/qcd/action/fermion/implementation/WilsonKernelsHandImplementation.h b/Grid/qcd/action/fermion/implementation/WilsonKernelsHandImplementation.h
index 89ae5668..688cb75a 100644
--- a/Grid/qcd/action/fermion/implementation/WilsonKernelsHandImplementation.h
+++ b/Grid/qcd/action/fermion/implementation/WilsonKernelsHandImplementation.h
@@ -76,7 +76,24 @@ Author: paboyle <paboyle@ph.ed.ac.uk>
 
 #define REGISTER
 
-#define LOAD_CHIMU \
+#ifdef GRID_SIMT
+#define LOAD_CHIMU(ptype)		\
+  {const SiteSpinor & ref (in[offset]);	\
+    Chimu_00=coalescedReadPermute<ptype>(ref()(0)(0),perm);	\
+    Chimu_01=coalescedReadPermute<ptype>(ref()(0)(1),perm);	\
+    Chimu_02=coalescedReadPermute<ptype>(ref()(0)(2),perm);	\
+    Chimu_10=coalescedReadPermute<ptype>(ref()(1)(0),perm);	\
+    Chimu_11=coalescedReadPermute<ptype>(ref()(1)(1),perm);	\
+    Chimu_12=coalescedReadPermute<ptype>(ref()(1)(2),perm);	\
+    Chimu_20=coalescedReadPermute<ptype>(ref()(2)(0),perm);	\
+    Chimu_21=coalescedReadPermute<ptype>(ref()(2)(1),perm);	\
+    Chimu_22=coalescedReadPermute<ptype>(ref()(2)(2),perm);	\
+    Chimu_30=coalescedReadPermute<ptype>(ref()(3)(0),perm);	\
+    Chimu_31=coalescedReadPermute<ptype>(ref()(3)(1),perm);	\
+    Chimu_32=coalescedReadPermute<ptype>(ref()(3)(2),perm);	}
+#define PERMUTE_DIR(dir) ;
+#else
+#define LOAD_CHIMU(ptype)		\
   {const SiteSpinor & ref (in[offset]);	\
     Chimu_00=ref()(0)(0);\
     Chimu_01=ref()(0)(1);\
@@ -91,55 +108,55 @@ Author: paboyle <paboyle@ph.ed.ac.uk>
     Chimu_31=ref()(3)(1);\
     Chimu_32=ref()(3)(2);}
 
-#define LOAD_CHI\
-  {const SiteHalfSpinor &ref(buf[offset]);	\
-    Chi_00 = ref()(0)(0);\
-    Chi_01 = ref()(0)(1);\
-    Chi_02 = ref()(0)(2);\
-    Chi_10 = ref()(1)(0);\
-    Chi_11 = ref()(1)(1);\
-    Chi_12 = ref()(1)(2);}
-
-// To splat or not to splat depends on the implementation
-#define MULT_2SPIN(A)\
-  {auto & ref(U[sU](A));			\
-   Impl::loadLinkElement(U_00,ref()(0,0));	\
-   Impl::loadLinkElement(U_10,ref()(1,0));	\
-   Impl::loadLinkElement(U_20,ref()(2,0));	\
-   Impl::loadLinkElement(U_01,ref()(0,1));	\
-   Impl::loadLinkElement(U_11,ref()(1,1));	\
-   Impl::loadLinkElement(U_21,ref()(2,1));	\
-    UChi_00 = U_00*Chi_00;\
-    UChi_10 = U_00*Chi_10;\
-    UChi_01 = U_10*Chi_00;\
-    UChi_11 = U_10*Chi_10;\
-    UChi_02 = U_20*Chi_00;\
-    UChi_12 = U_20*Chi_10;\
-    UChi_00+= U_01*Chi_01;\
-    UChi_10+= U_01*Chi_11;\
-    UChi_01+= U_11*Chi_01;\
-    UChi_11+= U_11*Chi_11;\
-    UChi_02+= U_21*Chi_01;\
-    UChi_12+= U_21*Chi_11;\
-    Impl::loadLinkElement(U_00,ref()(0,2));	\
-    Impl::loadLinkElement(U_10,ref()(1,2));	\
-    Impl::loadLinkElement(U_20,ref()(2,2));	\
-    UChi_00+= U_00*Chi_02;\
-    UChi_10+= U_00*Chi_12;\
-    UChi_01+= U_10*Chi_02;\
-    UChi_11+= U_10*Chi_12;\
-    UChi_02+= U_20*Chi_02;\
-    UChi_12+= U_20*Chi_12;}
-
-
 #define PERMUTE_DIR(dir)			\
-      permute##dir(Chi_00,Chi_00);\
+  permute##dir(Chi_00,Chi_00);	\
       permute##dir(Chi_01,Chi_01);\
       permute##dir(Chi_02,Chi_02);\
-      permute##dir(Chi_10,Chi_10);\
+      permute##dir(Chi_10,Chi_10);	\
       permute##dir(Chi_11,Chi_11);\
       permute##dir(Chi_12,Chi_12);
 
+#endif
+
+#define LOAD_CHI				\
+  {const SiteHalfSpinor &ref(buf[offset]);	\
+    Chi_00 = coalescedRead(ref()(0)(0));	\
+    Chi_01 = coalescedRead(ref()(0)(1));	\
+    Chi_02 = coalescedRead(ref()(0)(2));	\
+    Chi_10 = coalescedRead(ref()(1)(0));	\
+    Chi_11 = coalescedRead(ref()(1)(1));	\
+    Chi_12 = coalescedRead(ref()(1)(2));}
+
+#define MULT_2SPIN(A)\
+  {auto & ref(U[sU](A));					\
+  U_00=coalescedRead(ref()(0,0));				\
+  U_10=coalescedRead(ref()(1,0));					\
+  U_20=coalescedRead(ref()(2,0));					\
+  U_01=coalescedRead(ref()(0,1));					\
+  U_11=coalescedRead(ref()(1,1));					\
+  U_21=coalescedRead(ref()(2,1));					\
+    UChi_00 = U_00*Chi_00;					\
+    UChi_10 = U_00*Chi_10;					\
+    UChi_01 = U_10*Chi_00;					\
+    UChi_11 = U_10*Chi_10;					\
+    UChi_02 = U_20*Chi_00;					\
+    UChi_12 = U_20*Chi_10;					\
+    UChi_00+= U_01*Chi_01;					\
+    UChi_10+= U_01*Chi_11;					\
+    UChi_01+= U_11*Chi_01;					\
+    UChi_11+= U_11*Chi_11;					\
+    UChi_02+= U_21*Chi_01;					\
+    UChi_12+= U_21*Chi_11;					\
+    U_00=coalescedRead(ref()(0,2));				\
+    U_10=coalescedRead(ref()(1,2));				\
+    U_20=coalescedRead(ref()(2,2));				\
+    UChi_00+= U_00*Chi_02;					\
+    UChi_10+= U_00*Chi_12;					\
+    UChi_01+= U_10*Chi_02;					\
+    UChi_11+= U_10*Chi_12;					\
+    UChi_02+= U_20*Chi_02;					\
+    UChi_12+= U_20*Chi_12;}
+
 //      hspin(0)=fspin(0)+timesI(fspin(3));
 //      hspin(1)=fspin(1)+timesI(fspin(2));
 #define XP_PROJ \
@@ -359,7 +376,7 @@ Author: paboyle <paboyle@ph.ed.ac.uk>
   local  = SE->_is_local;			\
   perm   = SE->_permute;			\
   if ( local ) {				\
-    LOAD_CHIMU;					\
+    LOAD_CHIMU(PERM);				\
     PROJ;					\
     if ( perm) {				\
       PERMUTE_DIR(PERM);			\
@@ -376,7 +393,7 @@ Author: paboyle <paboyle@ph.ed.ac.uk>
   local  = SE->_is_local;			\
   perm   = SE->_permute;			\
   if ( local ) {				\
-    LOAD_CHIMU;					\
+    LOAD_CHIMU(PERM);				\
     PROJ;					\
     if ( perm) {				\
       PERMUTE_DIR(PERM);			\
@@ -401,40 +418,39 @@ Author: paboyle <paboyle@ph.ed.ac.uk>
 
 #define HAND_RESULT(ss)				\
   {						\
-    SiteSpinor & ref (out[ss]);		\
-    vstream(ref()(0)(0),result_00);		\
-    vstream(ref()(0)(1),result_01);		\
-    vstream(ref()(0)(2),result_02);		\
-    vstream(ref()(1)(0),result_10);		\
-    vstream(ref()(1)(1),result_11);		\
-    vstream(ref()(1)(2),result_12);		\
-    vstream(ref()(2)(0),result_20);		\
-    vstream(ref()(2)(1),result_21);		\
-    vstream(ref()(2)(2),result_22);		\
-    vstream(ref()(3)(0),result_30);		\
-    vstream(ref()(3)(1),result_31);		\
-    vstream(ref()(3)(2),result_32);		\
+    SiteSpinor & ref (out[ss]);			\
+    coalescedWrite(ref()(0)(0),result_00);		\
+    coalescedWrite(ref()(0)(1),result_01);		\
+    coalescedWrite(ref()(0)(2),result_02);		\
+    coalescedWrite(ref()(1)(0),result_10);		\
+    coalescedWrite(ref()(1)(1),result_11);		\
+    coalescedWrite(ref()(1)(2),result_12);		\
+    coalescedWrite(ref()(2)(0),result_20);		\
+    coalescedWrite(ref()(2)(1),result_21);		\
+    coalescedWrite(ref()(2)(2),result_22);		\
+    coalescedWrite(ref()(3)(0),result_30);		\
+    coalescedWrite(ref()(3)(1),result_31);		\
+    coalescedWrite(ref()(3)(2),result_32);		\
   }
 
-#define HAND_RESULT_EXT(ss)			\
-  if (nmu){					\
-    SiteSpinor & ref (out[ss]);		\
-    ref()(0)(0)+=result_00;		\
-    ref()(0)(1)+=result_01;		\
-    ref()(0)(2)+=result_02;		\
-    ref()(1)(0)+=result_10;		\
-    ref()(1)(1)+=result_11;		\
-    ref()(1)(2)+=result_12;		\
-    ref()(2)(0)+=result_20;		\
-    ref()(2)(1)+=result_21;		\
-    ref()(2)(2)+=result_22;		\
-    ref()(3)(0)+=result_30;		\
-    ref()(3)(1)+=result_31;		\
-    ref()(3)(2)+=result_32;		\
+#define HAND_RESULT_EXT(ss)				\
+  {							\
+    SiteSpinor & ref (out[ss]);				\
+    coalescedWrite(ref()(0)(0),coalescedRead(ref()(0)(0))+result_00);	\
+    coalescedWrite(ref()(0)(1),coalescedRead(ref()(0)(1))+result_01);	\
+    coalescedWrite(ref()(0)(2),coalescedRead(ref()(0)(2))+result_02);	\
+    coalescedWrite(ref()(1)(0),coalescedRead(ref()(1)(0))+result_10);	\
+    coalescedWrite(ref()(1)(1),coalescedRead(ref()(1)(1))+result_11);	\
+    coalescedWrite(ref()(1)(2),coalescedRead(ref()(1)(2))+result_12);	\
+    coalescedWrite(ref()(2)(0),coalescedRead(ref()(2)(0))+result_20);	\
+    coalescedWrite(ref()(2)(1),coalescedRead(ref()(2)(1))+result_21);	\
+    coalescedWrite(ref()(2)(2),coalescedRead(ref()(2)(2))+result_22);	\
+    coalescedWrite(ref()(3)(0),coalescedRead(ref()(3)(0))+result_30);	\
+    coalescedWrite(ref()(3)(1),coalescedRead(ref()(3)(1))+result_31);	\
+    coalescedWrite(ref()(3)(2),coalescedRead(ref()(3)(2))+result_32);	\
   }
 
-
-#define HAND_DECLARATIONS(a)			\
+#define HAND_DECLARATIONS(Simd)			\
   Simd result_00;				\
   Simd result_01;				\
   Simd result_02;				\
@@ -466,19 +482,19 @@ Author: paboyle <paboyle@ph.ed.ac.uk>
   Simd U_11;					\
   Simd U_21;
 
-#define ZERO_RESULT				\
-  result_00=Zero();				\
-  result_01=Zero();				\
-  result_02=Zero();				\
-  result_10=Zero();				\
-  result_11=Zero();				\
-  result_12=Zero();				\
-  result_20=Zero();				\
-  result_21=Zero();				\
-  result_22=Zero();				\
-  result_30=Zero();				\
-  result_31=Zero();				\
-  result_32=Zero();			
+#define ZERO_RESULT							\
+  zeroit(result_00);							\
+  zeroit(result_01);							\
+  zeroit(result_02);							\
+  zeroit(result_10);							\
+  zeroit(result_11);							\
+  zeroit(result_12);							\
+  zeroit(result_20);							\
+  zeroit(result_21);							\
+  zeroit(result_22);							\
+  zeroit(result_30);							\
+  zeroit(result_31);							\
+  zeroit(result_32);			
 
 #define Chimu_00 Chi_00
 #define Chimu_01 Chi_01
@@ -502,8 +518,8 @@ WilsonKernels<Impl>::HandDhopSite(StencilView &st, DoubledGaugeFieldView &U,Site
 // T==0, Z==1, Y==2, Z==3 expect 1,2,2,2 simd layout etc...
   typedef typename Simd::scalar_type S;
   typedef typename Simd::vector_type V;
-
-  HAND_DECLARATIONS(ignore);
+  typedef decltype( coalescedRead( in[0]()(0)(0) )) Simt;
+  HAND_DECLARATIONS(Simt);
 
   int offset,local,perm, ptype;
   StencilEntry *SE;
@@ -525,8 +541,8 @@ void WilsonKernels<Impl>::HandDhopSiteDag(StencilView &st,DoubledGaugeFieldView
 {
   typedef typename Simd::scalar_type S;
   typedef typename Simd::vector_type V;
-
-  HAND_DECLARATIONS(ignore);
+  typedef decltype( coalescedRead( in[0]()(0)(0) )) Simt;
+  HAND_DECLARATIONS(Simt);
 
   StencilEntry *SE;
   int offset,local,perm, ptype;
@@ -549,8 +565,8 @@ WilsonKernels<Impl>::HandDhopSiteInt(StencilView &st,DoubledGaugeFieldView &U,Si
 // T==0, Z==1, Y==2, Z==3 expect 1,2,2,2 simd layout etc...
   typedef typename Simd::scalar_type S;
   typedef typename Simd::vector_type V;
-
-  HAND_DECLARATIONS(ignore);
+  typedef decltype( coalescedRead( in[0]()(0)(0) )) Simt;
+  HAND_DECLARATIONS(Simt);
 
   int offset,local,perm, ptype;
   StencilEntry *SE;
@@ -572,8 +588,8 @@ void WilsonKernels<Impl>::HandDhopSiteDagInt(StencilView &st,DoubledGaugeFieldVi
 {
   typedef typename Simd::scalar_type S;
   typedef typename Simd::vector_type V;
-
-  HAND_DECLARATIONS(ignore);
+  typedef decltype( coalescedRead( in[0]()(0)(0) )) Simt;
+  HAND_DECLARATIONS(Simt);
 
   StencilEntry *SE;
   int offset,local,perm, ptype;
@@ -596,8 +612,8 @@ WilsonKernels<Impl>::HandDhopSiteExt(StencilView &st,DoubledGaugeFieldView &U,Si
 // T==0, Z==1, Y==2, Z==3 expect 1,2,2,2 simd layout etc...
   typedef typename Simd::scalar_type S;
   typedef typename Simd::vector_type V;
-
-  HAND_DECLARATIONS(ignore);
+  typedef decltype( coalescedRead( in[0]()(0)(0) )) Simt;
+  HAND_DECLARATIONS(Simt);
 
   int offset, ptype;
   StencilEntry *SE;
@@ -620,8 +636,8 @@ void WilsonKernels<Impl>::HandDhopSiteDagExt(StencilView &st,DoubledGaugeFieldVi
 {
   typedef typename Simd::scalar_type S;
   typedef typename Simd::vector_type V;
-
-  HAND_DECLARATIONS(ignore);
+  typedef decltype( coalescedRead( in[0]()(0)(0) )) Simt;
+  HAND_DECLARATIONS(Simt);
 
   StencilEntry *SE;
   int offset, ptype;
@@ -682,3 +698,4 @@ NAMESPACE_END(Grid);
 #undef HAND_RESULT
 #undef HAND_RESULT_INT
 #undef HAND_RESULT_EXT
+#undef HAND_DECLARATIONS
diff --git a/Grid/qcd/action/fermion/implementation/WilsonKernelsImplementation.h b/Grid/qcd/action/fermion/implementation/WilsonKernelsImplementation.h
index c5f50bbb..937d13af 100644
--- a/Grid/qcd/action/fermion/implementation/WilsonKernelsImplementation.h
+++ b/Grid/qcd/action/fermion/implementation/WilsonKernelsImplementation.h
@@ -445,20 +445,20 @@ void WilsonKernels<Impl>::DhopKernel(int Opt,StencilImpl &st,  DoubledGaugeField
 
    if( interior && exterior ) {
      if (Opt == WilsonKernelsStatic::OptGeneric    ) { KERNEL_CALL(GenericDhopSite); return;}
-#ifndef GRID_CUDA
      if (Opt == WilsonKernelsStatic::OptHandUnroll ) { KERNEL_CALL(HandDhopSite);    return;}
+#ifndef GRID_CUDA
      if (Opt == WilsonKernelsStatic::OptInlineAsm  ) {  ASM_CALL(AsmDhopSite);    return;}
 #endif
    } else if( interior ) {
      if (Opt == WilsonKernelsStatic::OptGeneric    ) { KERNEL_CALLNB(GenericDhopSiteInt); return;}
-#ifndef GRID_CUDA
      if (Opt == WilsonKernelsStatic::OptHandUnroll ) { KERNEL_CALLNB(HandDhopSiteInt);    return;}
+#ifndef GRID_CUDA
      if (Opt == WilsonKernelsStatic::OptInlineAsm  ) {  ASM_CALL(AsmDhopSiteInt);    return;}
 #endif
    } else if( exterior ) {
      if (Opt == WilsonKernelsStatic::OptGeneric    ) { KERNEL_CALL(GenericDhopSiteExt); return;}
-#ifndef GRID_CUDA
      if (Opt == WilsonKernelsStatic::OptHandUnroll ) { KERNEL_CALL(HandDhopSiteExt);    return;}
+#ifndef GRID_CUDA
      if (Opt == WilsonKernelsStatic::OptInlineAsm  ) {  ASM_CALL(AsmDhopSiteExt);    return;}
 #endif
    }
@@ -476,20 +476,20 @@ void WilsonKernels<Impl>::DhopKernel(int Opt,StencilImpl &st,  DoubledGaugeField
 
    if( interior && exterior ) {
      if (Opt == WilsonKernelsStatic::OptGeneric    ) { KERNEL_CALL(GenericDhopSiteDag); return;}
-#ifndef GRID_CUDA
      if (Opt == WilsonKernelsStatic::OptHandUnroll ) { KERNEL_CALL(HandDhopSiteDag);    return;}
+#ifndef GRID_CUDA
      if (Opt == WilsonKernelsStatic::OptInlineAsm  ) {  ASM_CALL(AsmDhopSiteDag);     return;}
 #endif
    } else if( interior ) {
      if (Opt == WilsonKernelsStatic::OptGeneric    ) { KERNEL_CALL(GenericDhopSiteDagInt); return;}
-#ifndef GRID_CUDA
      if (Opt == WilsonKernelsStatic::OptHandUnroll ) { KERNEL_CALL(HandDhopSiteDagInt);    return;}
+#ifndef GRID_CUDA
      if (Opt == WilsonKernelsStatic::OptInlineAsm  ) {  ASM_CALL(AsmDhopSiteDagInt);     return;}
 #endif
    } else if( exterior ) {
      if (Opt == WilsonKernelsStatic::OptGeneric    ) { KERNEL_CALL(GenericDhopSiteDagExt); return;}
-#ifndef GRID_CUDA
      if (Opt == WilsonKernelsStatic::OptHandUnroll ) { KERNEL_CALL(HandDhopSiteDagExt);    return;}
+#ifndef GRID_CUDA
      if (Opt == WilsonKernelsStatic::OptInlineAsm  ) {  ASM_CALL(AsmDhopSiteDagExt);     return;}
 #endif
    }
diff --git a/Grid/qcd/action/gauge/GaugeImplTypes.h b/Grid/qcd/action/gauge/GaugeImplTypes.h
index 55a20eca..2499e0e9 100644
--- a/Grid/qcd/action/gauge/GaugeImplTypes.h
+++ b/Grid/qcd/action/gauge/GaugeImplTypes.h
@@ -96,7 +96,7 @@ public:
   ///////////////////////////////////////////////////////////
   // Move these to another class
   // HMC auxiliary functions
-  static inline void generate_momenta(Field &P, GridParallelRNG &pRNG) 
+  static inline void generate_momenta(Field &P, GridSerialRNG & sRNG, GridParallelRNG &pRNG) 
   {
     // Zbigniew Srocinsky thesis:
     //
diff --git a/Grid/qcd/action/gauge/PlaqPlusRectangleAction.h b/Grid/qcd/action/gauge/PlaqPlusRectangleAction.h
index 639aca19..7690092d 100644
--- a/Grid/qcd/action/gauge/PlaqPlusRectangleAction.h
+++ b/Grid/qcd/action/gauge/PlaqPlusRectangleAction.h
@@ -49,7 +49,7 @@ public:
 
   virtual std::string action_name(){return "PlaqPlusRectangleAction";}
       
-  virtual void refresh(const GaugeField &U, GridParallelRNG& pRNG) {}; // noop as no pseudoferms
+  virtual void refresh(const GaugeField &U, GridSerialRNG &sRNG, GridParallelRNG& pRNG) {}; // noop as no pseudoferms
       
   virtual std::string LogParameters(){
     std::stringstream sstream;
diff --git a/Grid/qcd/action/gauge/WilsonGaugeAction.h b/Grid/qcd/action/gauge/WilsonGaugeAction.h
index 40d600d2..f535b54f 100644
--- a/Grid/qcd/action/gauge/WilsonGaugeAction.h
+++ b/Grid/qcd/action/gauge/WilsonGaugeAction.h
@@ -54,8 +54,7 @@ public:
     return sstream.str();
   }
 
-  virtual void refresh(const GaugeField &U,
-                       GridParallelRNG &pRNG){};  // noop as no pseudoferms
+  virtual void refresh(const GaugeField &U, GridSerialRNG &sRNG, GridParallelRNG &pRNG){};  // noop as no pseudoferms
 
   virtual RealD S(const GaugeField &U) {
     RealD plaq = WilsonLoops<Gimpl>::avgPlaquette(U);
diff --git a/Grid/qcd/action/pseudofermion/ExactOneFlavourRatio.h b/Grid/qcd/action/pseudofermion/ExactOneFlavourRatio.h
index 9fc0a3b0..576a8cf6 100644
--- a/Grid/qcd/action/pseudofermion/ExactOneFlavourRatio.h
+++ b/Grid/qcd/action/pseudofermion/ExactOneFlavourRatio.h
@@ -124,7 +124,7 @@ NAMESPACE_BEGIN(Grid);
       //
       // As a check of rational require \Phi^dag M_{EOFA} \Phi == eta^dag M^-1/2^dag M M^-1/2 eta = eta^dag eta
       //
-      virtual void refresh(const GaugeField& U, GridParallelRNG& pRNG)
+      virtual void refresh(const GaugeField& U, GridSerialRNG &sRNG, GridParallelRNG& pRNG)
       {
         Lop.ImportGauge(U);
         Rop.ImportGauge(U);
diff --git a/Grid/qcd/action/pseudofermion/OneFlavourEvenOddRational.h b/Grid/qcd/action/pseudofermion/OneFlavourEvenOddRational.h
index 56dff94d..656e9b2f 100644
--- a/Grid/qcd/action/pseudofermion/OneFlavourEvenOddRational.h
+++ b/Grid/qcd/action/pseudofermion/OneFlavourEvenOddRational.h
@@ -1,4 +1,3 @@
-
 /*************************************************************************************
 
 Grid physics library, www.github.com/paboyle/Grid
@@ -43,8 +42,7 @@ NAMESPACE_BEGIN(Grid);
 //
 
 template <class Impl>
-class OneFlavourEvenOddRationalPseudoFermionAction
-  : public Action<typename Impl::GaugeField> {
+class OneFlavourEvenOddRationalPseudoFermionAction : public Action<typename Impl::GaugeField> {
 public:
   INHERIT_IMPL_TYPES(Impl);
 
@@ -103,7 +101,7 @@ public:
     return sstream.str();
   }
   
-  virtual void refresh(const GaugeField &U, GridParallelRNG &pRNG) {
+  virtual void refresh(const GaugeField &U, GridSerialRNG &sRNG, GridParallelRNG &pRNG) {
     // P(phi) = e^{- phi^dag (MpcdagMpc)^-1/2 phi}
     //        = e^{- phi^dag (MpcdagMpc)^-1/4 (MpcdagMpc)^-1/4 phi}
     // Phi = MpcdagMpc^{1/4} eta
@@ -156,7 +154,10 @@ public:
 
     msCG(Mpc, PhiOdd, Y);
 
-    if ( (rand()%param.BoundsCheckFreq)==0 ) { 
+    auto grid = FermOp.FermionGrid();
+    auto r=rand();
+    grid->Broadcast(0,r);
+    if ( (r%param.BoundsCheckFreq)==0 ) { 
       FermionField gauss(FermOp.FermionRedBlackGrid());
       gauss = PhiOdd;
       HighBoundCheck(Mpc,gauss,param.hi);
diff --git a/Grid/qcd/action/pseudofermion/OneFlavourEvenOddRationalRatio.h b/Grid/qcd/action/pseudofermion/OneFlavourEvenOddRationalRatio.h
index e5f0b602..e968b8e4 100644
--- a/Grid/qcd/action/pseudofermion/OneFlavourEvenOddRationalRatio.h
+++ b/Grid/qcd/action/pseudofermion/OneFlavourEvenOddRationalRatio.h
@@ -101,7 +101,7 @@ NAMESPACE_BEGIN(Grid);
       }
       
       
-      virtual void refresh(const GaugeField &U, GridParallelRNG& pRNG) {
+      virtual void refresh(const GaugeField &U, GridSerialRNG &sRNG, GridParallelRNG& pRNG) {
 
 	// S_f = chi^dag* P(V^dag*V)/Q(V^dag*V)* N(M^dag*M)/D(M^dag*M)* P(V^dag*V)/Q(V^dag*V)* chi       
 	//
@@ -170,7 +170,10 @@ NAMESPACE_BEGIN(Grid);
 	msCG_M(MdagM,X,Y);
 
 	// Randomly apply rational bounds checks.
-	if ( (rand()%param.BoundsCheckFreq)==0 ) { 
+	auto grid = NumOp.FermionGrid();
+        auto r=rand();
+        grid->Broadcast(0,r);
+        if ( (r%param.BoundsCheckFreq)==0 ) { 
 	  FermionField gauss(NumOp.FermionRedBlackGrid());
 	  gauss = PhiOdd;
 	  HighBoundCheck(MdagM,gauss,param.hi);
diff --git a/Grid/qcd/action/pseudofermion/OneFlavourRational.h b/Grid/qcd/action/pseudofermion/OneFlavourRational.h
index f6c823c9..aa647445 100644
--- a/Grid/qcd/action/pseudofermion/OneFlavourRational.h
+++ b/Grid/qcd/action/pseudofermion/OneFlavourRational.h
@@ -98,7 +98,7 @@ NAMESPACE_BEGIN(Grid);
 
 
       
-      virtual void refresh(const GaugeField &U, GridParallelRNG& pRNG) {
+      virtual void refresh(const GaugeField &U, GridSerialRNG &sRNG, GridParallelRNG& pRNG) {
 
 	
 	// P(phi) = e^{- phi^dag (MdagM)^-1/2 phi}
@@ -142,7 +142,10 @@ NAMESPACE_BEGIN(Grid);
 
 	msCG(MdagMOp,Phi,Y);
 
-	if ( (rand()%param.BoundsCheckFreq)==0 ) { 
+	auto grid = FermOp.FermionGrid();
+        auto r=rand();
+        grid->Broadcast(0,r);
+        if ( (r%param.BoundsCheckFreq)==0 ) { 
 	  FermionField gauss(FermOp.FermionGrid());
 	  gauss = Phi;
 	  HighBoundCheck(MdagMOp,gauss,param.hi);
diff --git a/Grid/qcd/action/pseudofermion/OneFlavourRationalRatio.h b/Grid/qcd/action/pseudofermion/OneFlavourRationalRatio.h
index 5fae2fe9..128c869a 100644
--- a/Grid/qcd/action/pseudofermion/OneFlavourRationalRatio.h
+++ b/Grid/qcd/action/pseudofermion/OneFlavourRationalRatio.h
@@ -95,7 +95,7 @@ NAMESPACE_BEGIN(Grid);
       }
       
 
-      virtual void refresh(const GaugeField &U, GridParallelRNG& pRNG) {
+      virtual void refresh(const GaugeField &U, GridSerialRNG &sRNG, GridParallelRNG& pRNG) {
 
 	// S_f = chi^dag* P(V^dag*V)/Q(V^dag*V)* N(M^dag*M)/D(M^dag*M)* P(V^dag*V)/Q(V^dag*V)* chi       
 	//
@@ -156,7 +156,10 @@ NAMESPACE_BEGIN(Grid);
 	msCG_M(MdagM,X,Y);
 
 	// Randomly apply rational bounds checks.
-	if ( (rand()%param.BoundsCheckFreq)==0 ) { 
+        auto grid = NumOp.FermionGrid();
+        auto r=rand();
+        grid->Broadcast(0,r);
+        if ( (r%param.BoundsCheckFreq)==0 ) { 	
 	  FermionField gauss(NumOp.FermionGrid());
 	  gauss = Phi;
 	  HighBoundCheck(MdagM,gauss,param.hi);
diff --git a/Grid/qcd/action/pseudofermion/TwoFlavour.h b/Grid/qcd/action/pseudofermion/TwoFlavour.h
index f905a675..2ac97ddd 100644
--- a/Grid/qcd/action/pseudofermion/TwoFlavour.h
+++ b/Grid/qcd/action/pseudofermion/TwoFlavour.h
@@ -73,7 +73,7 @@ public:
   //////////////////////////////////////////////////////////////////////////////////////
   // Push the gauge field in to the dops. Assume any BC's and smearing already applied
   //////////////////////////////////////////////////////////////////////////////////////
-  virtual void refresh(const GaugeField &U, GridParallelRNG &pRNG) {
+  virtual void refresh(const GaugeField &U, GridSerialRNG &sRNG, GridParallelRNG &pRNG) {
     // P(phi) = e^{- phi^dag (MdagM)^-1 phi}
     // Phi = Mdag eta
     // P(eta) = e^{- eta^dag eta}
diff --git a/Grid/qcd/action/pseudofermion/TwoFlavourEvenOdd.h b/Grid/qcd/action/pseudofermion/TwoFlavourEvenOdd.h
index a3cf8f08..2e5208a8 100644
--- a/Grid/qcd/action/pseudofermion/TwoFlavourEvenOdd.h
+++ b/Grid/qcd/action/pseudofermion/TwoFlavourEvenOdd.h
@@ -77,7 +77,7 @@ public:
   //////////////////////////////////////////////////////////////////////////////////////
   // Push the gauge field in to the dops. Assume any BC's and smearing already applied
   //////////////////////////////////////////////////////////////////////////////////////
-  virtual void refresh(const GaugeField &U, GridParallelRNG& pRNG) {
+  virtual void refresh(const GaugeField &U, GridSerialRNG &sRNG, GridParallelRNG& pRNG) {
     
     // P(phi) = e^{- phi^dag (MpcdagMpc)^-1 phi}
     // Phi = McpDag eta 
diff --git a/Grid/qcd/action/pseudofermion/TwoFlavourEvenOddRatio.h b/Grid/qcd/action/pseudofermion/TwoFlavourEvenOddRatio.h
index d1d6f336..da628c75 100644
--- a/Grid/qcd/action/pseudofermion/TwoFlavourEvenOddRatio.h
+++ b/Grid/qcd/action/pseudofermion/TwoFlavourEvenOddRatio.h
@@ -84,7 +84,7 @@ NAMESPACE_BEGIN(Grid);
       } 
 
       
-      virtual void refresh(const GaugeField &U, GridParallelRNG& pRNG) {
+      virtual void refresh(const GaugeField &U, GridSerialRNG &sRNG, GridParallelRNG& pRNG) {
 
         // P(phi) = e^{- phi^dag Vpc (MpcdagMpc)^-1 Vpcdag phi}
         //
diff --git a/Grid/qcd/action/pseudofermion/TwoFlavourRatio.h b/Grid/qcd/action/pseudofermion/TwoFlavourRatio.h
index 4d72faba..f584706d 100644
--- a/Grid/qcd/action/pseudofermion/TwoFlavourRatio.h
+++ b/Grid/qcd/action/pseudofermion/TwoFlavourRatio.h
@@ -64,7 +64,7 @@ public:
     return sstream.str();
   }  
       
-  virtual void refresh(const GaugeField &U, GridParallelRNG& pRNG) {
+  virtual void refresh(const GaugeField &U, GridSerialRNG &sRNG, GridParallelRNG& pRNG) {
 
     // P(phi) = e^{- phi^dag V (MdagM)^-1 Vdag phi}
     //
diff --git a/Grid/qcd/action/scalar/ScalarAction.h b/Grid/qcd/action/scalar/ScalarAction.h
index 34fc4fac..8b4f4f79 100644
--- a/Grid/qcd/action/scalar/ScalarAction.h
+++ b/Grid/qcd/action/scalar/ScalarAction.h
@@ -55,7 +55,7 @@ public:
   }
   virtual std::string action_name() {return "ScalarAction";}
 
-  virtual void refresh(const Field &U, GridParallelRNG &pRNG) {}  // noop as no pseudoferms
+  virtual void refresh(const Field &U, GridSerialRNG &sRNG, GridParallelRNG &pRNG) {}  // noop as no pseudoferms
 
   virtual RealD S(const Field &p) {
     return (mass_square * 0.5 + Nd) * ScalarObs<Impl>::sumphisquared(p) +
diff --git a/Grid/qcd/action/scalar/ScalarImpl.h b/Grid/qcd/action/scalar/ScalarImpl.h
index 403ea573..13bd6c90 100644
--- a/Grid/qcd/action/scalar/ScalarImpl.h
+++ b/Grid/qcd/action/scalar/ScalarImpl.h
@@ -27,7 +27,7 @@ public:
   typedef Field              FermionField;
   typedef Field              PropagatorField;
     
-  static inline void generate_momenta(Field& P, GridParallelRNG& pRNG){
+  static inline void generate_momenta(Field& P, GridSerialRNG &sRNG, GridParallelRNG& pRNG){
     RealD scale = ::sqrt(HMC_MOMENTUM_DENOMINATOR); // CPS/UKQCD momentum rescaling
     gaussian(pRNG, P);
     P *= scale; 
@@ -151,7 +151,7 @@ public:
       out = one / out;
     }
 
-    static inline void generate_momenta(Field &P, GridParallelRNG &pRNG)
+    static inline void generate_momenta(Field &P, GridSerialRNG & sRNG, GridParallelRNG &pRNG)
     {
       RealD scale = ::sqrt(HMC_MOMENTUM_DENOMINATOR); // CPS/UKQCD momentum rescaling
 #ifndef USE_FFT_ACCELERATION
diff --git a/Grid/qcd/action/scalar/ScalarInteractionAction.h b/Grid/qcd/action/scalar/ScalarInteractionAction.h
index 5a5f9251..e04dd486 100644
--- a/Grid/qcd/action/scalar/ScalarInteractionAction.h
+++ b/Grid/qcd/action/scalar/ScalarInteractionAction.h
@@ -77,7 +77,7 @@ public:
 
   virtual std::string action_name() { return "ScalarAction"; }
 
-  virtual void refresh(const Field &U, GridParallelRNG &pRNG) {}
+  virtual void refresh(const Field &U, GridSerialRNG & sRNG, GridParallelRNG &pRNG) {}
 
   virtual RealD S(const Field &p)
   {
diff --git a/Grid/qcd/hmc/HMC.h b/Grid/qcd/hmc/HMC.h
index f168b69a..44674ea5 100644
--- a/Grid/qcd/hmc/HMC.h
+++ b/Grid/qcd/hmc/HMC.h
@@ -139,7 +139,7 @@ private:
   // Evolution
   /////////////////////////////////////////////////////////
   RealD evolve_hmc_step(Field &U) {
-    TheIntegrator.refresh(U, pRNG);  // set U and initialize P and phi's
+    TheIntegrator.refresh(U, sRNG, pRNG);  // set U and initialize P and phi's
 
     RealD H0 = TheIntegrator.S(U);  // initial state action
 
diff --git a/Grid/qcd/hmc/integrators/Integrator.h b/Grid/qcd/hmc/integrators/Integrator.h
index 70055754..aa28c6c8 100644
--- a/Grid/qcd/hmc/integrators/Integrator.h
+++ b/Grid/qcd/hmc/integrators/Integrator.h
@@ -33,6 +33,7 @@ directory
 #define INTEGRATOR_INCLUDED
 
 #include <memory>
+#include "MomentumFilter.h"
 
 NAMESPACE_BEGIN(Grid);
 
@@ -78,8 +79,19 @@ protected:
   RepresentationPolicy Representations;
   IntegratorParameters Params;
 
+  //Filters allow the user to manipulate the conjugate momentum, for example to freeze links in DDHMC
+  //It is applied whenever the momentum is updated / refreshed
+  //The default filter does nothing
+  MomentumFilterBase<MomentaField> const* MomFilter;
+
   const ActionSet<Field, RepresentationPolicy> as;
 
+  //Get a pointer to a shared static instance of the "do-nothing" momentum filter to serve as a default
+  static MomentumFilterBase<MomentaField> const* getDefaultMomFilter(){ 
+    static MomentumFilterNone<MomentaField> filter;
+    return &filter;
+  }
+
   void update_P(Field& U, int level, double ep) 
   {
     t_P[level] += ep;
@@ -135,6 +147,8 @@ protected:
 
     // Force from the other representations
     as[level].apply(update_P_hireps, Representations, Mom, U, ep);
+
+    MomFilter->applyFilter(Mom);
   }
 
   void update_U(Field& U, double ep) 
@@ -174,11 +188,23 @@ public:
     t_P.resize(levels, 0.0);
     t_U = 0.0;
     // initialization of smearer delegated outside of Integrator
+
+    //Default the momentum filter to "do-nothing"
+    MomFilter = getDefaultMomFilter();
   };
 
   virtual ~Integrator() {}
 
   virtual std::string integrator_name() = 0;
+  
+  //Set the momentum filter allowing for manipulation of the conjugate momentum
+  void setMomentumFilter(const MomentumFilterBase<MomentaField> &filter){
+    MomFilter = &filter;
+  }
+
+  //Access the conjugate momentum
+  const MomentaField & getMomentum() const{ return P; }
+  
 
   void print_parameters()
   {
@@ -210,10 +236,9 @@ public:
   // over the representations
   struct _refresh {
     template <class FieldType, class Repr>
-    void operator()(std::vector<Action<FieldType>*> repr_set, Repr& Rep,
-                    GridParallelRNG& pRNG) {
+    void operator()(std::vector<Action<FieldType>*> repr_set, Repr& Rep, GridSerialRNG & sRNG, GridParallelRNG& pRNG) {
       for (int a = 0; a < repr_set.size(); ++a){
-        repr_set.at(a)->refresh(Rep.U, pRNG);
+        repr_set.at(a)->refresh(Rep.U, sRNG, pRNG);
       
 	std::cout << GridLogDebug << "Hirep refreshing pseudofermions" << std::endl;
       }
@@ -221,12 +246,12 @@ public:
   } refresh_hireps{};
 
   // Initialization of momenta and actions
-  void refresh(Field& U, GridParallelRNG& pRNG) 
+  void refresh(Field& U,  GridSerialRNG & sRNG, GridParallelRNG& pRNG) 
   {
     assert(P.Grid() == U.Grid());
     std::cout << GridLogIntegrator << "Integrator refresh\n";
 
-    FieldImplementation::generate_momenta(P, pRNG);
+    FieldImplementation::generate_momenta(P, sRNG, pRNG);
 
     // Update the smeared fields, can be implemented as observer
     // necessary to keep the fields updated even after a reject
@@ -243,12 +268,14 @@ public:
         // get gauge field from the SmearingPolicy and
         // based on the boolean is_smeared in actionID
         Field& Us = Smearer.get_U(as[level].actions.at(actionID)->is_smeared);
-        as[level].actions.at(actionID)->refresh(Us, pRNG);
+        as[level].actions.at(actionID)->refresh(Us, sRNG, pRNG);
       }
 
       // Refresh the higher representation actions
-      as[level].apply(refresh_hireps, Representations, pRNG);
+      as[level].apply(refresh_hireps, Representations, sRNG, pRNG);
     }
+
+    MomFilter->applyFilter(P);
   }
 
   // to be used by the actionlevel class to iterate
diff --git a/Grid/qcd/hmc/integrators/MomentumFilter.h b/Grid/qcd/hmc/integrators/MomentumFilter.h
new file mode 100644
index 00000000..2a15d80c
--- /dev/null
+++ b/Grid/qcd/hmc/integrators/MomentumFilter.h
@@ -0,0 +1,94 @@
+/*************************************************************************************
+
+Grid physics library, www.github.com/paboyle/Grid
+
+Source file: ./lib/qcd/hmc/integrators/MomentumFilter.h
+
+Copyright (C) 2015
+
+Author: Christopher Kelly <ckelly@bnl.gov>
+Author: Peter Boyle <paboyle@ph.ed.ac.uk>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+See the full license in the file "LICENSE" in the top level distribution
+directory
+*************************************************************************************/
+/*  END LEGAL */
+//--------------------------------------------------------------------
+#ifndef MOMENTUM_FILTER
+#define MOMENTUM_FILTER
+
+NAMESPACE_BEGIN(Grid);
+
+//These filter objects allow the user to manipulate the conjugate momentum as part of the update / refresh
+
+template<typename MomentaField>
+struct MomentumFilterBase{
+  virtual void applyFilter(MomentaField &P) const;
+};
+
+//Do nothing
+template<typename MomentaField>
+struct MomentumFilterNone: public MomentumFilterBase<MomentaField>{
+  void applyFilter(MomentaField &P) const override{}
+};
+
+//Multiply each site/direction by a Lorentz vector complex number field
+//Can be used to implement a mask, zeroing out sites
+template<typename MomentaField>
+struct MomentumFilterApplyPhase: public MomentumFilterBase<MomentaField>{
+  typedef typename MomentaField::vector_type vector_type; //SIMD-vectorized complex type
+  typedef typename MomentaField::scalar_type scalar_type; //scalar complex type
+  typedef iVector<iScalar<iScalar<vector_type> >, Nd > LorentzScalarType; //complex phase for each site/direction
+  typedef Lattice<LorentzScalarType> LatticeLorentzScalarType;
+  
+  LatticeLorentzScalarType phase;
+ 
+  MomentumFilterApplyPhase(const LatticeLorentzScalarType _phase): phase(_phase){}
+
+  //Default to uniform field of (1,0)
+  MomentumFilterApplyPhase(GridBase* _grid): phase(_grid){
+    LorentzScalarType one;
+    for(int mu=0;mu<Nd;mu++)
+      one(mu)()() = scalar_type(1.);
+    
+    phase = one;
+  }
+
+  void applyFilter(MomentaField &P) const override{
+    conformable(P,phase);
+    autoView( P_v , P, AcceleratorWrite);
+    autoView( phase_v , phase, AcceleratorRead);
+
+    accelerator_for(ss,P_v.size(),MomentaField::vector_type::Nsimd(),{
+    	auto site_mom = P_v(ss);
+    	auto site_phase = phase_v(ss);
+	for(int mu=0;mu<Nd;mu++)
+	  site_mom(mu) = site_mom(mu) * site_phase(mu);
+    	coalescedWrite(P_v[ss], site_mom);
+      });
+    
+  }
+
+
+};
+
+
+
+
+NAMESPACE_END(Grid);
+
+#endif
diff --git a/Grid/simd/Grid_gpu_vec.h b/Grid/simd/Grid_gpu_vec.h
index 8e55ce2f..b2c7588f 100644
--- a/Grid/simd/Grid_gpu_vec.h
+++ b/Grid/simd/Grid_gpu_vec.h
@@ -60,11 +60,26 @@ template<class pair>
 class GpuComplex {
 public:
   pair z;
-  typedef decltype(z.x) real;
+  typedef decltype(z.x) Real;
 public: 
   accelerator_inline GpuComplex() = default;
-  accelerator_inline GpuComplex(real re,real im) { z.x=re; z.y=im; };
+  accelerator_inline GpuComplex(Real re,Real im) { z.x=re; z.y=im; };
   accelerator_inline GpuComplex(const GpuComplex &zz) { z = zz.z;};
+  accelerator_inline Real real(void) const { return z.x; };
+  accelerator_inline Real imag(void) const { return z.y; };
+  accelerator_inline GpuComplex &operator=(const Zero &zz) { z.x = 0; z.y=0; return *this; };
+  accelerator_inline GpuComplex &operator*=(const GpuComplex &r) {
+    *this = (*this) * r;
+    return *this;
+  }
+  accelerator_inline GpuComplex &operator+=(const GpuComplex &r) {
+    *this = (*this) + r;
+    return *this;
+  }
+  accelerator_inline GpuComplex &operator-=(const GpuComplex &r) {
+    *this = (*this) - r;
+    return *this;
+  }
   friend accelerator_inline  GpuComplex operator+(const GpuComplex &lhs,const GpuComplex &rhs) { 
     GpuComplex r ; 
     r.z.x = lhs.z.x + rhs.z.x; 
@@ -157,6 +172,11 @@ typedef GpuVector<NSIMD_RealD,    double      > GpuVectorRD;
 typedef GpuVector<NSIMD_ComplexD, GpuComplexD > GpuVectorCD;
 typedef GpuVector<NSIMD_Integer,  Integer     > GpuVectorI;
 
+accelerator_inline GpuComplexF timesI(const GpuComplexF &r)     { return(GpuComplexF(-r.imag(),r.real()));}
+accelerator_inline GpuComplexD timesI(const GpuComplexD &r)     { return(GpuComplexD(-r.imag(),r.real()));}
+accelerator_inline GpuComplexF timesMinusI(const GpuComplexF &r){ return(GpuComplexF(r.imag(),-r.real()));}
+accelerator_inline GpuComplexD timesMinusI(const GpuComplexD &r){ return(GpuComplexD(r.imag(),-r.real()));}
+
 accelerator_inline float half2float(half h)
 {
   float f;
diff --git a/Grid/simd/Simd.h b/Grid/simd/Simd.h
index 1dc86c1b..76ca3bef 100644
--- a/Grid/simd/Simd.h
+++ b/Grid/simd/Simd.h
@@ -148,10 +148,14 @@ accelerator_inline void sub (ComplexF * __restrict__ y,const ComplexF * __restri
 accelerator_inline void add (ComplexF * __restrict__ y,const ComplexF * __restrict__ l,const ComplexF *__restrict__ r){ *y = (*l) + (*r); }
   
 //conjugate already supported for complex
-accelerator_inline ComplexF timesI(const ComplexF &r)     { return(r*ComplexF(0.0,1.0));}
-accelerator_inline ComplexD timesI(const ComplexD &r)     { return(r*ComplexD(0.0,1.0));}
-accelerator_inline ComplexF timesMinusI(const ComplexF &r){ return(r*ComplexF(0.0,-1.0));}
-accelerator_inline ComplexD timesMinusI(const ComplexD &r){ return(r*ComplexD(0.0,-1.0));}
+accelerator_inline ComplexF timesI(const ComplexF &r)     { return(ComplexF(-r.imag(),r.real()));}
+accelerator_inline ComplexD timesI(const ComplexD &r)     { return(ComplexD(-r.imag(),r.real()));}
+accelerator_inline ComplexF timesMinusI(const ComplexF &r){ return(ComplexF(r.imag(),-r.real()));}
+accelerator_inline ComplexD timesMinusI(const ComplexD &r){ return(ComplexD(r.imag(),-r.real()));}
+//accelerator_inline ComplexF timesI(const ComplexF &r)     { return(r*ComplexF(0.0,1.0));}
+//accelerator_inline ComplexD timesI(const ComplexD &r)     { return(r*ComplexD(0.0,1.0));}
+//accelerator_inline ComplexF timesMinusI(const ComplexF &r){ return(r*ComplexF(0.0,-1.0));}
+//accelerator_inline ComplexD timesMinusI(const ComplexD &r){ return(r*ComplexD(0.0,-1.0));}
 
 // define projections to real and imaginay parts
 accelerator_inline ComplexF projReal(const ComplexF &r){return( ComplexF(r.real(), 0.0));}
diff --git a/Grid/stencil/SimpleCompressor.h b/Grid/stencil/SimpleCompressor.h
index be7c89c0..2ce48369 100644
--- a/Grid/stencil/SimpleCompressor.h
+++ b/Grid/stencil/SimpleCompressor.h
@@ -7,20 +7,20 @@ template<class vobj>
 class SimpleCompressor {
 public:
   void Point(int) {};
-  accelerator_inline int  CommDatumSize(void) { return sizeof(vobj); }
-  accelerator_inline bool DecompressionStep(void) { return false; }
-  template<class cobj> accelerator_inline void Compress(cobj *buf,int o,const cobj &in) { buf[o]=in; }
-  accelerator_inline void Exchange(vobj *mp,vobj *vp0,vobj *vp1,Integer type,Integer o){
+  accelerator_inline int  CommDatumSize(void) const { return sizeof(vobj); }
+  accelerator_inline bool DecompressionStep(void) const { return false; }
+  template<class cobj> accelerator_inline void Compress(cobj *buf,int o,const cobj &in) const { buf[o]=in; }
+  accelerator_inline void Exchange(vobj *mp,vobj *vp0,vobj *vp1,Integer type,Integer o) const {
     exchange(mp[2*o],mp[2*o+1],vp0[o],vp1[o],type);
   }
-  accelerator_inline void Decompress(vobj *out,vobj *in, int o){ assert(0); }
+  accelerator_inline void Decompress(vobj *out,vobj *in, int o) const { assert(0); }
   accelerator_inline void CompressExchange(vobj *out0,vobj *out1,const vobj *in,
-			       int j,int k, int m,int type){
+			       int j,int k, int m,int type) const {
     exchange(out0[j],out1[j],in[k],in[m],type);
   }
   // For cshift. Cshift should drop compressor coupling altogether 
   // because I had to decouple the code from the Stencil anyway
-  accelerator_inline vobj operator() (const vobj &arg) {
+  accelerator_inline vobj operator() (const vobj &arg) const {
     return arg;
   }
 };
diff --git a/Grid/stencil/Stencil.h b/Grid/stencil/Stencil.h
index 23fc8203..58cebed3 100644
--- a/Grid/stencil/Stencil.h
+++ b/Grid/stencil/Stencil.h
@@ -147,16 +147,16 @@ class CartesianStencilAccelerator {
   cobj* u_recv_buf_p;
   cobj* u_send_buf_p;
 
-  accelerator_inline cobj *CommBuf(void) { return u_recv_buf_p; }
+  accelerator_inline cobj *CommBuf(void) const { return u_recv_buf_p; }
 
-  accelerator_inline int GetNodeLocal(int osite,int point) {
+  accelerator_inline int GetNodeLocal(int osite,int point) const {
     return this->_entries_p[point+this->_npoints*osite]._is_local;
   }
-  accelerator_inline StencilEntry * GetEntry(int &ptype,int point,int osite) {
+  accelerator_inline StencilEntry * GetEntry(int &ptype,int point,int osite) const {
     ptype = this->_permute_type[point]; return & this->_entries_p[point+this->_npoints*osite];
   }
 
-  accelerator_inline uint64_t GetInfo(int &ptype,int &local,int &perm,int point,int ent,uint64_t base) {
+  accelerator_inline uint64_t GetInfo(int &ptype,int &local,int &perm,int point,int ent,uint64_t base) const {
     uint64_t cbase = (uint64_t)&u_recv_buf_p[0];
     local = this->_entries_p[ent]._is_local;
     perm  = this->_entries_p[ent]._permute;
@@ -168,14 +168,14 @@ class CartesianStencilAccelerator {
     }
   }
 
-  accelerator_inline uint64_t GetPFInfo(int ent,uint64_t base) {
+  accelerator_inline uint64_t GetPFInfo(int ent,uint64_t base) const {
     uint64_t cbase = (uint64_t)&u_recv_buf_p[0];
     int local = this->_entries_p[ent]._is_local;
     if (local) return  base + this->_entries_p[ent]._byte_offset;
     else       return cbase + this->_entries_p[ent]._byte_offset;
   }
 
-  accelerator_inline void iCoorFromIindex(Coordinate &coor,int lane)
+  accelerator_inline void iCoorFromIindex(Coordinate &coor,int lane) const
   {
     Lexicographic::CoorFromIndex(coor,lane,this->_simd_layout);
   }
@@ -221,7 +221,7 @@ public:
   typedef typename cobj::vector_type vector_type;
   typedef typename cobj::scalar_type scalar_type;
   typedef typename cobj::scalar_object scalar_object;
-  typedef CartesianStencilView<vobj,cobj,Parameters> View_type;
+  typedef const CartesianStencilView<vobj,cobj,Parameters> View_type;
   typedef typename View_type::StencilVector StencilVector;
   ///////////////////////////////////////////
   // Helper structs
diff --git a/Grid/tensors/Tensor_SIMT.h b/Grid/tensors/Tensor_SIMT.h
index ec57a679..672f385f 100644
--- a/Grid/tensors/Tensor_SIMT.h
+++ b/Grid/tensors/Tensor_SIMT.h
@@ -64,6 +64,70 @@ void coalescedWriteNonTemporal(vobj & __restrict__ vec,const vobj & __restrict__
 }
 #else
 
+
+#ifndef GRID_SYCL
+// Use the scalar as our own complex on GPU ... thrust::complex or std::complex
+template<class vsimd,IfSimd<vsimd> = 0> accelerator_inline
+typename vsimd::scalar_type
+coalescedRead(const vsimd & __restrict__ vec,int lane=acceleratorSIMTlane(vsimd::Nsimd()))
+{
+  typedef typename vsimd::scalar_type S;
+  S * __restrict__ p=(S *)&vec;
+  return p[lane];
+}
+template<int ptype,class vsimd,IfSimd<vsimd> = 0> accelerator_inline
+typename vsimd::scalar_type
+coalescedReadPermute(const vsimd & __restrict__ vec,int doperm,int lane=acceleratorSIMTlane(vsimd::Nsimd()))
+{
+  typedef typename vsimd::scalar_type S;
+
+  S * __restrict__ p=(S *)&vec;
+  int mask = vsimd::Nsimd() >> (ptype + 1);
+  int plane= doperm ? lane ^ mask : lane;
+  return p[plane];
+}
+template<class vsimd,IfSimd<vsimd> = 0> accelerator_inline
+void coalescedWrite(vsimd & __restrict__ vec,
+		    const typename vsimd::scalar_type & __restrict__ extracted,
+		    int lane=acceleratorSIMTlane(vsimd::Nsimd()))
+{
+  typedef typename vsimd::scalar_type S;
+  S * __restrict__ p=(S *)&vec;
+  p[lane]=extracted;
+}
+#else
+// For SyCL have option to use GpuComplex from inside the vector type in SIMT loops
+// Faster for some reason
+template<class vsimd,IfSimd<vsimd> = 0> accelerator_inline
+typename vsimd::vector_type::datum
+coalescedRead(const vsimd & __restrict__ vec,int lane=acceleratorSIMTlane(vsimd::Nsimd()))
+{
+  typedef typename vsimd::vector_type::datum S;
+  S * __restrict__ p=(S *)&vec;
+  return p[lane];
+}
+template<int ptype,class vsimd,IfSimd<vsimd> = 0> accelerator_inline
+typename vsimd::vector_type::datum
+coalescedReadPermute(const vsimd & __restrict__ vec,int doperm,int lane=acceleratorSIMTlane(vsimd::Nsimd()))
+{
+  typedef typename vsimd::vector_type::datum S;
+
+  S * __restrict__ p=(S *)&vec;
+  int mask = vsimd::Nsimd() >> (ptype + 1);
+  int plane= doperm ? lane ^ mask : lane;
+  return p[plane];
+}
+template<class vsimd,IfSimd<vsimd> = 0> accelerator_inline
+void coalescedWrite(vsimd & __restrict__ vec,
+		    const typename vsimd::vector_type::datum & __restrict__ extracted,
+		    int lane=acceleratorSIMTlane(vsimd::Nsimd()))
+{
+  typedef typename vsimd::vector_type::datum S;
+  S * __restrict__ p=(S *)&vec;
+  p[lane]=extracted;
+}
+#endif
+
 //////////////////////////////////////////
 // Extract and insert slices on the GPU
 //////////////////////////////////////////
diff --git a/Grid/threads/Accelerator.h b/Grid/threads/Accelerator.h
index 59645546..f1a694fb 100644
--- a/Grid/threads/Accelerator.h
+++ b/Grid/threads/Accelerator.h
@@ -104,7 +104,7 @@ extern int acceleratorAbortOnGpuError;
 
 accelerator_inline int acceleratorSIMTlane(int Nsimd) {
 #ifdef GRID_SIMT
-  return threadIdx.z; 
+  return threadIdx.x; 
 #else
   return 0;
 #endif
@@ -112,28 +112,67 @@ accelerator_inline int acceleratorSIMTlane(int Nsimd) {
 
 #define accelerator_for2dNB( iter1, num1, iter2, num2, nsimd, ... )	\
   {									\
+    int nt=acceleratorThreads();					\
     typedef uint64_t Iterator;						\
     auto lambda = [=] accelerator					\
       (Iterator iter1,Iterator iter2,Iterator lane) mutable {		\
       __VA_ARGS__;							\
     };									\
-    int nt=acceleratorThreads();					\
-    dim3 cu_threads(acceleratorThreads(),1,nsimd);			\
+    dim3 cu_threads(nsimd,acceleratorThreads(),1);			\
     dim3 cu_blocks ((num1+nt-1)/nt,num2,1);				\
     LambdaApply<<<cu_blocks,cu_threads>>>(num1,num2,nsimd,lambda);	\
   }
 
+#define accelerator_for6dNB(iter1, num1,				\
+                            iter2, num2,				\
+                            iter3, num3,				\
+                            iter4, num4,				\
+                            iter5, num5,				\
+			    iter6, num6, ... )				\
+  {									\
+    typedef uint64_t Iterator;						\
+    auto lambda = [=] accelerator					\
+      (Iterator iter1,Iterator iter2,					\
+       Iterator iter3,Iterator iter4,					\
+       Iterator iter5,Iterator iter6) mutable {				\
+      __VA_ARGS__;							\
+    };									\
+    dim3 cu_blocks (num1,num2,num3);					\
+    dim3 cu_threads(num4,num5,num6);					\
+    Lambda6Apply<<<cu_blocks,cu_threads>>>(num1,num2,num3,num4,num5,num6,lambda); \
+  }
+
 template<typename lambda>  __global__
 void LambdaApply(uint64_t num1, uint64_t num2, uint64_t num3, lambda Lambda)
 {
-  uint64_t x = threadIdx.x + blockDim.x*blockIdx.x;
-  uint64_t y = threadIdx.y + blockDim.y*blockIdx.y;
-  uint64_t z = threadIdx.z;
+  // Weird permute is to make lane coalesce for large blocks
+  uint64_t x = threadIdx.y + blockDim.y*blockIdx.x;
+  uint64_t y = threadIdx.z + blockDim.z*blockIdx.y;
+  uint64_t z = threadIdx.x;
   if ( (x < num1) && (y<num2) && (z<num3) ) {
     Lambda(x,y,z);
   }
 }
 
+template<typename lambda>  __global__
+void Lambda6Apply(uint64_t num1, uint64_t num2, uint64_t num3,
+		  uint64_t num4, uint64_t num5, uint64_t num6,
+		  lambda Lambda)
+{
+  uint64_t iter1 = blockIdx.x;
+  uint64_t iter2 = blockIdx.y;
+  uint64_t iter3 = blockIdx.z;
+  uint64_t iter4 = threadIdx.x;
+  uint64_t iter5 = threadIdx.y;
+  uint64_t iter6 = threadIdx.z;
+
+  if ( (iter1 < num1) && (iter2<num2) && (iter3<num3)
+    && (iter4 < num4) && (iter5<num5) && (iter6<num6) )
+  {
+    Lambda(iter1,iter2,iter3,iter4,iter5,iter6);
+  }
+}
+
 #define accelerator_barrier(dummy)					\
   {									\
     cudaDeviceSynchronize();						\
@@ -221,7 +260,7 @@ accelerator_inline int acceleratorSIMTlane(int Nsimd) {
       cl::sycl::range<3> global{unum1,unum2,nsimd};			\
       cgh.parallel_for<class dslash>(					\
       cl::sycl::nd_range<3>(global,local), \
-      [=] (cl::sycl::nd_item<3> item) mutable {       \
+      [=] (cl::sycl::nd_item<3> item) /*mutable*/ {   \
       auto iter1    = item.get_global_id(0);	      \
       auto iter2    = item.get_global_id(1);	      \
       auto lane     = item.get_global_id(2);	      \
@@ -417,7 +456,7 @@ accelerator_inline void acceleratorSynchronise(void)
   __syncwarp();
 #endif
 #ifdef GRID_SYCL
-  // No barrier call on SYCL??  // Option get __spir:: stuff to do warp barrier
+  cl::sycl::detail::workGroupBarrier();
 #endif
 #ifdef GRID_HIP
   __syncthreads();
diff --git a/benchmarks/Benchmark_dwf_fp32.cc b/benchmarks/Benchmark_dwf_fp32.cc
index cb86177e..03f3ee61 100644
--- a/benchmarks/Benchmark_dwf_fp32.cc
+++ b/benchmarks/Benchmark_dwf_fp32.cc
@@ -53,7 +53,7 @@ int main (int argc, char ** argv)
   int threads = GridThread::GetThreads();
 
   Coordinate latt4 = GridDefaultLatt();
-  int Ls=8;
+  int Ls=16;
   for(int i=0;i<argc;i++)
     if(std::string(argv[i]) == "-Ls"){
       std::stringstream ss(argv[i+1]); ss >> Ls;
diff --git a/configure.ac b/configure.ac
index fb0c78fc..5f165412 100644
--- a/configure.ac
+++ b/configure.ac
@@ -140,12 +140,23 @@ AC_ARG_ENABLE([gparity],
      [ac_GPARITY=${enable_gparity}], [ac_GPARITY=yes])
 
 AM_CONDITIONAL(BUILD_GPARITY, [ test "${ac_GPARITY}X" == "yesX" ])
+
+AC_ARG_ENABLE([zmobius],
+     [AC_HELP_STRING([--enable-zmobius=yes|no], [enable Zmobius support])],
+     [ac_ZMOBIUS=${enable_zmobius}], [ac_ZMOBIUS=yes])
+
+AM_CONDITIONAL(BUILD_ZMOBIUS, [ test "${ac_ZMOBIUS}X" == "yesX" ])
+
+
 case ${ac_FERMION_REPS} in
    yes) AC_DEFINE([ENABLE_FERMION_REPS],[1],[non QCD fermion reps]);;
 esac
 case ${ac_GPARITY} in
    yes) AC_DEFINE([ENABLE_GPARITY],[1],[fermion actions with GPARITY BCs]);;
 esac
+case ${ac_ZMOBIUS} in
+   yes) AC_DEFINE([ENABLE_ZMOBIUS],[1],[Zmobius fermion actions]);;
+esac
 ############### Nc
 AC_ARG_ENABLE([Nc],
     [AC_HELP_STRING([--enable-Nc=2|3|4], [enable number of colours])],
diff --git a/tests/forces/Test_momentum_filter.cc b/tests/forces/Test_momentum_filter.cc
new file mode 100644
index 00000000..856ea0f2
--- /dev/null
+++ b/tests/forces/Test_momentum_filter.cc
@@ -0,0 +1,154 @@
+    /*************************************************************************************
+
+    Grid physics library, www.github.com/paboyle/Grid 
+
+    Source file: ./tests/Test_wilson_force.cc
+
+    Copyright (C) 2015
+
+Author: Christopher Kelly <ckelly@bnl.gov>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+    See the full license in the file "LICENSE" in the top level distribution directory
+    *************************************************************************************/
+    /*  END LEGAL */
+#include <Grid/Grid.h>
+
+using namespace std;
+using namespace Grid;
+
+//Get the mu-directected links on the upper boundary and the bulk remainder
+template<typename Field>
+void getLinksBoundaryBulk(Field &bound, Field &bulk,  Field &from, const Coordinate &latt_size){
+  bound = Zero(); bulk = Zero();
+  for(int mu=0;mu<Nd;mu++){
+    LatticeInteger mucoor(bound.Grid());
+    LatticeCoordinate(mucoor, mu);
+
+    bound = where( mucoor == (Integer)(latt_size[mu] - 1), from, bound );
+    bulk = where( mucoor != (Integer)(latt_size[mu] - 1), from, bulk );
+  }
+}
+
+
+int main (int argc, char ** argv)
+{
+  Grid_init(&argc,&argv);
+
+  Coordinate latt_size   = GridDefaultLatt();
+  Coordinate simd_layout = GridDefaultSimd(Nd,vComplex::Nsimd());
+  Coordinate mpi_layout  = GridDefaultMpi();
+
+  GridCartesian               Grid(latt_size,simd_layout,mpi_layout);
+  GridRedBlackCartesian     RBGrid(&Grid);
+
+  int threads = GridThread::GetThreads();
+  std::cout<<GridLogMessage << "Grid is setup to use "<<threads<<" threads"<<std::endl;
+
+  std::vector<int> seeds({1,2,3,4});
+
+  GridParallelRNG          pRNG(&Grid);
+  pRNG.SeedFixedIntegers(seeds);
+
+  typedef PeriodicGimplR Gimpl;
+  typedef WilsonGaugeAction<Gimpl> GaugeAction;
+  typedef NoHirep Representation; //fundamental
+  typedef NoSmearing<Gimpl> Smearing;
+  typedef MinimumNorm2<Gimpl, Smearing> Omelyan;
+  typedef Gimpl::Field Field;
+  typedef MomentumFilterApplyPhase<Field> Filter;
+  Filter filter(&Grid);
+  
+  //Setup a filter that disables link update on links passing through the global lattice boundary
+  typedef Filter::LatticeLorentzScalarType MaskType;
+  typedef Filter::LorentzScalarType MaskSiteType;
+
+  MaskSiteType zero, one;
+  for(int mu=0;mu<Nd;mu++){
+    zero(mu)()() = 0.;
+    one(mu)()() = 1.;
+  }
+  MaskType zeroField(&Grid), oneField(&Grid);
+  zeroField = zero;
+  oneField = one;
+
+  
+  filter.phase = oneField; //make every site 1.0
+
+  //Zero mu-directed links at upper boundary
+  for(int mu=0;mu<Nd;mu++){
+    LatticeInteger mucoor(&Grid);
+    LatticeCoordinate(mucoor, mu);
+    
+    filter.phase = where( mucoor == (Integer)(latt_size[mu] - 1) , zeroField, filter.phase );
+  }
+
+  //Start with a random gauge field
+  Field U(&Grid);
+  SU<Nc>::HotConfiguration(pRNG,U);
+
+  //Get the original links on the bulk and boundary for later use
+  Field Ubnd_orig(&Grid), Ubulk_orig(&Grid);
+  getLinksBoundaryBulk(Ubnd_orig, Ubulk_orig, U, latt_size);
+
+  ActionSet<Field,Representation> actions(1);  
+  double beta=6;
+  GaugeAction gauge_action(beta);
+  actions[0].push_back(&gauge_action);
+
+  Smearing smear;
+  IntegratorParameters params(1,1.); //1 MD step
+  Omelyan integrator(&Grid, params, actions, smear);
+  
+  integrator.setMomentumFilter(filter);
+
+  integrator.refresh(U, pRNG); //doesn't actually change the gauge field
+
+  //Check the momentum is zero on the boundary
+  const auto &P = integrator.getMomentum();
+  Field Pbnd(&Grid), Pbulk(&Grid);
+  getLinksBoundaryBulk(Pbnd, Pbulk, const_cast<Field&>(P), latt_size);
+
+  RealD Pbnd_nrm = norm2(Pbnd); //expect zero
+  std::cout << GridLogMessage << "After refresh, norm2 of mu-directed conjugate momentum on boundary is: " << Pbnd_nrm << " (expect 0)" << std::endl;
+  RealD Pbulk_nrm = norm2(Pbulk); //expect non-zero
+  std::cout << GridLogMessage << "After refresh, norm2 of bulk conjugate momentum is: " << Pbulk_nrm << " (expect non-zero)" << std::endl;
+
+  //Evolve the gauge field
+  integrator.integrate(U);
+
+  //Check momentum is still zero on boundary
+  getLinksBoundaryBulk(Pbnd, Pbulk, const_cast<Field&>(P), latt_size);
+  
+  Pbnd_nrm = norm2(Pbnd); //expect zero
+  std::cout << GridLogMessage << "After integrate, norm2 of mu-directed conjugate momentum on boundary is: " << Pbnd_nrm << " (expect 0)" << std::endl;
+  Pbulk_nrm = norm2(Pbulk); //expect non-zero
+  std::cout << GridLogMessage << "After integrate, norm2 of bulk conjugate momentum is: " << Pbulk_nrm << " (expect non-zero)" << std::endl;
+
+  //Get the new bulk and bound links
+  Field Ubnd_new(&Grid), Ubulk_new(&Grid);
+  getLinksBoundaryBulk(Ubnd_new, Ubulk_new, U, latt_size);
+
+  Field Ubnd_diff = Ubnd_new - Ubnd_orig;
+  Field Ubulk_diff = Ubulk_new - Ubulk_orig;
+
+  RealD Ubnd_change = norm2( Ubnd_diff );
+  RealD Ubulk_change = norm2( Ubulk_diff );
+  std::cout << GridLogMessage << "After integrate, norm2 of change in mu-directed boundary links is : " << Ubnd_change << " (expect 0)" << std::endl;
+  std::cout << GridLogMessage << "After integrate, norm2 of change in bulk links is : " << Ubulk_change << " (expect non-zero)" << std::endl;
+
+  Grid_finalize();
+}