diff --git a/FDTD/engine_ext_upml.cpp b/FDTD/engine_ext_upml.cpp
index f3e8548..b99afe4 100644
--- a/FDTD/engine_ext_upml.cpp
+++ b/FDTD/engine_ext_upml.cpp
@@ -20,6 +20,7 @@
 #include "engine.h"
 #include "engine_sse.h"
 #include "tools/array_ops.h"
+#include "tools/useful.h"
 
 Engine_Ext_UPML::Engine_Ext_UPML(Operator_Ext_UPML* op_ext) : Engine_Extension(op_ext)
 {
@@ -32,6 +33,8 @@ Engine_Ext_UPML::Engine_Ext_UPML(Operator_Ext_UPML* op_ext) : Engine_Extension(o
 	volt_flux = Create_N_3DArray<FDTD_FLOAT>(m_Op_UPML->m_numLines);
 	curr = Create_N_3DArray<FDTD_FLOAT>(m_Op_UPML->m_numLines);
 	curr_flux = Create_N_3DArray<FDTD_FLOAT>(m_Op_UPML->m_numLines);
+
+	SetNumberOfThreads(1);
 }
 
 Engine_Ext_UPML::~Engine_Ext_UPML()
@@ -46,19 +49,35 @@ Engine_Ext_UPML::~Engine_Ext_UPML()
 	curr_flux=NULL;
 }
 
-void Engine_Ext_UPML::DoPreVoltageUpdates()
+void Engine_Ext_UPML::SetNumberOfThreads(int nrThread)
+{
+	Engine_Extension::SetNumberOfThreads(nrThread);
+
+	m_numX = AssignJobs2Threads(m_Op_UPML->m_numLines[0],m_NrThreads,false);
+	m_start.resize(m_NrThreads,0);
+	m_start.at(0)=0;
+	for (size_t n=1;n<m_numX.size();++n)
+		m_start.at(n) = m_start.at(n-1) + m_numX.at(n-1);
+}
+
+
+void Engine_Ext_UPML::DoPreVoltageUpdates(int threadID)
 {
 	if (m_Eng==NULL)
 		return;
 
+	if (threadID>=m_NrThreads)
+		return;
+
 	unsigned int pos[3];
 	unsigned int loc_pos[3];
 	switch (m_Eng->GetType())
 	{
 	case Engine::BASIC:
 		{
-			for (loc_pos[0]=0;loc_pos[0]<m_Op_UPML->m_numLines[0];++loc_pos[0])
+			for (unsigned int lineX=0;lineX<m_numX.at(threadID);++lineX)
 			{
+				loc_pos[0]=lineX+m_start.at(threadID);
 				pos[0] = loc_pos[0] + m_Op_UPML->m_StartPos[0];
 				for (loc_pos[1]=0;loc_pos[1]<m_Op_UPML->m_numLines[1];++loc_pos[1])
 				{
@@ -85,37 +104,39 @@ void Engine_Ext_UPML::DoPreVoltageUpdates()
 		}
 	case Engine::SSE:
 		{
-		Engine_sse* eng_sse = (Engine_sse*) m_Eng;
-		for (loc_pos[0]=0;loc_pos[0]<m_Op_UPML->m_numLines[0];++loc_pos[0])
-		{
-			pos[0] = loc_pos[0] + m_Op_UPML->m_StartPos[0];
-			for (loc_pos[1]=0;loc_pos[1]<m_Op_UPML->m_numLines[1];++loc_pos[1])
+			Engine_sse* eng_sse = (Engine_sse*) m_Eng;
+			for (unsigned int lineX=0;lineX<m_numX.at(threadID);++lineX)
 			{
-				pos[1] = loc_pos[1] + m_Op_UPML->m_StartPos[1];
-				for (loc_pos[2]=0;loc_pos[2]<m_Op_UPML->m_numLines[2];++loc_pos[2])
+				loc_pos[0]=lineX+m_start.at(threadID);
+				pos[0] = loc_pos[0] + m_Op_UPML->m_StartPos[0];
+				for (loc_pos[1]=0;loc_pos[1]<m_Op_UPML->m_numLines[1];++loc_pos[1])
 				{
-					pos[2] = loc_pos[2] + m_Op_UPML->m_StartPos[2];
+					pos[1] = loc_pos[1] + m_Op_UPML->m_StartPos[1];
+					for (loc_pos[2]=0;loc_pos[2]<m_Op_UPML->m_numLines[2];++loc_pos[2])
+					{
+						pos[2] = loc_pos[2] + m_Op_UPML->m_StartPos[2];
 
-					volt[0][loc_pos[0]][loc_pos[1]][loc_pos[2]] = m_Op_UPML->vv[0][loc_pos[0]][loc_pos[1]][loc_pos[2]]   * eng_sse->Engine_sse::GetVolt(0,pos)
-																- m_Op_UPML->vvfo[0][loc_pos[0]][loc_pos[1]][loc_pos[2]] * volt_flux[0][loc_pos[0]][loc_pos[1]][loc_pos[2]];
-					eng_sse->Engine_sse::SetVolt(0,pos, volt_flux[0][loc_pos[0]][loc_pos[1]][loc_pos[2]]);
+						volt[0][loc_pos[0]][loc_pos[1]][loc_pos[2]] = m_Op_UPML->vv[0][loc_pos[0]][loc_pos[1]][loc_pos[2]]   * eng_sse->Engine_sse::GetVolt(0,pos)
+																	- m_Op_UPML->vvfo[0][loc_pos[0]][loc_pos[1]][loc_pos[2]] * volt_flux[0][loc_pos[0]][loc_pos[1]][loc_pos[2]];
+						eng_sse->Engine_sse::SetVolt(0,pos, volt_flux[0][loc_pos[0]][loc_pos[1]][loc_pos[2]]);
 
-					volt[1][loc_pos[0]][loc_pos[1]][loc_pos[2]] = m_Op_UPML->vv[1][loc_pos[0]][loc_pos[1]][loc_pos[2]]   * eng_sse->Engine_sse::GetVolt(1,pos)
-																- m_Op_UPML->vvfo[1][loc_pos[0]][loc_pos[1]][loc_pos[2]] * volt_flux[1][loc_pos[0]][loc_pos[1]][loc_pos[2]];
-					eng_sse->Engine_sse::SetVolt(1,pos, volt_flux[1][loc_pos[0]][loc_pos[1]][loc_pos[2]]);
+						volt[1][loc_pos[0]][loc_pos[1]][loc_pos[2]] = m_Op_UPML->vv[1][loc_pos[0]][loc_pos[1]][loc_pos[2]]   * eng_sse->Engine_sse::GetVolt(1,pos)
+																	- m_Op_UPML->vvfo[1][loc_pos[0]][loc_pos[1]][loc_pos[2]] * volt_flux[1][loc_pos[0]][loc_pos[1]][loc_pos[2]];
+						eng_sse->Engine_sse::SetVolt(1,pos, volt_flux[1][loc_pos[0]][loc_pos[1]][loc_pos[2]]);
 
-					volt[2][loc_pos[0]][loc_pos[1]][loc_pos[2]] = m_Op_UPML->vv[2][loc_pos[0]][loc_pos[1]][loc_pos[2]]   * eng_sse->Engine_sse::GetVolt(2,pos)
-																- m_Op_UPML->vvfo[2][loc_pos[0]][loc_pos[1]][loc_pos[2]] * volt_flux[2][loc_pos[0]][loc_pos[1]][loc_pos[2]];
-					eng_sse->Engine_sse::SetVolt(2,pos, volt_flux[2][loc_pos[0]][loc_pos[1]][loc_pos[2]]);
+						volt[2][loc_pos[0]][loc_pos[1]][loc_pos[2]] = m_Op_UPML->vv[2][loc_pos[0]][loc_pos[1]][loc_pos[2]]   * eng_sse->Engine_sse::GetVolt(2,pos)
+																	- m_Op_UPML->vvfo[2][loc_pos[0]][loc_pos[1]][loc_pos[2]] * volt_flux[2][loc_pos[0]][loc_pos[1]][loc_pos[2]];
+						eng_sse->Engine_sse::SetVolt(2,pos, volt_flux[2][loc_pos[0]][loc_pos[1]][loc_pos[2]]);
+					}
 				}
 			}
-		}
-		break;
+			break;
 		}
 	default:
 		{
-			for (loc_pos[0]=0;loc_pos[0]<m_Op_UPML->m_numLines[0];++loc_pos[0])
+			for (unsigned int lineX=0;lineX<m_numX.at(threadID);++lineX)
 			{
+				loc_pos[0]=lineX+m_start.at(threadID);
 				pos[0] = loc_pos[0] + m_Op_UPML->m_StartPos[0];
 				for (loc_pos[1]=0;loc_pos[1]<m_Op_UPML->m_numLines[1];++loc_pos[1])
 				{
@@ -143,10 +164,12 @@ void Engine_Ext_UPML::DoPreVoltageUpdates()
 
 }
 
-void Engine_Ext_UPML::DoPostVoltageUpdates()
+void Engine_Ext_UPML::DoPostVoltageUpdates(int threadID)
 {
 	if (m_Eng==NULL)
 		return;
+	if (threadID>=m_NrThreads)
+		return;
 
 	unsigned int pos[3];
 	unsigned int loc_pos[3];
@@ -155,8 +178,9 @@ void Engine_Ext_UPML::DoPostVoltageUpdates()
 	{
 	case Engine::BASIC:
 		{
-			for (loc_pos[0]=0;loc_pos[0]<m_Op_UPML->m_numLines[0];++loc_pos[0])
+			for (unsigned int lineX=0;lineX<m_numX.at(threadID);++lineX)
 			{
+				loc_pos[0]=lineX+m_start.at(threadID);
 				pos[0] = loc_pos[0] + m_Op_UPML->m_StartPos[0];
 				for (loc_pos[1]=0;loc_pos[1]<m_Op_UPML->m_numLines[1];++loc_pos[1])
 				{
@@ -181,8 +205,9 @@ void Engine_Ext_UPML::DoPostVoltageUpdates()
 	case Engine::SSE:
 		{
 			Engine_sse* eng_sse = (Engine_sse*) m_Eng;
-			for (loc_pos[0]=0;loc_pos[0]<m_Op_UPML->m_numLines[0];++loc_pos[0])
+			for (unsigned int lineX=0;lineX<m_numX.at(threadID);++lineX)
 			{
+				loc_pos[0]=lineX+m_start.at(threadID);
 				pos[0] = loc_pos[0] + m_Op_UPML->m_StartPos[0];
 				for (loc_pos[1]=0;loc_pos[1]<m_Op_UPML->m_numLines[1];++loc_pos[1])
 				{
@@ -206,8 +231,9 @@ void Engine_Ext_UPML::DoPostVoltageUpdates()
 		}
 	default:
 		{
-			for (loc_pos[0]=0;loc_pos[0]<m_Op_UPML->m_numLines[0];++loc_pos[0])
+			for (unsigned int lineX=0;lineX<m_numX.at(threadID);++lineX)
 			{
+				loc_pos[0]=lineX+m_start.at(threadID);
 				pos[0] = loc_pos[0] + m_Op_UPML->m_StartPos[0];
 				for (loc_pos[1]=0;loc_pos[1]<m_Op_UPML->m_numLines[1];++loc_pos[1])
 				{
@@ -232,10 +258,12 @@ void Engine_Ext_UPML::DoPostVoltageUpdates()
 
 }
 
-void Engine_Ext_UPML::DoPreCurrentUpdates()
+void Engine_Ext_UPML::DoPreCurrentUpdates(int threadID)
 {
 	if (m_Eng==NULL)
 		return;
+	if (threadID>=m_NrThreads)
+		return;
 
 	unsigned int pos[3];
 	unsigned int loc_pos[3];
@@ -245,8 +273,9 @@ void Engine_Ext_UPML::DoPreCurrentUpdates()
 	{
 	case Engine::BASIC:
 		{
-			for (loc_pos[0]=0;loc_pos[0]<m_Op_UPML->m_numLines[0];++loc_pos[0])
+			for (unsigned int lineX=0;lineX<m_numX.at(threadID);++lineX)
 			{
+				loc_pos[0]=lineX+m_start.at(threadID);
 				pos[0] = loc_pos[0] + m_Op_UPML->m_StartPos[0];
 				for (loc_pos[1]=0;loc_pos[1]<m_Op_UPML->m_numLines[1];++loc_pos[1])
 				{
@@ -274,8 +303,9 @@ void Engine_Ext_UPML::DoPreCurrentUpdates()
 	case Engine::SSE:
 		{
 			Engine_sse* eng_sse = (Engine_sse*) m_Eng;
-			for (loc_pos[0]=0;loc_pos[0]<m_Op_UPML->m_numLines[0];++loc_pos[0])
+			for (unsigned int lineX=0;lineX<m_numX.at(threadID);++lineX)
 			{
+				loc_pos[0]=lineX+m_start.at(threadID);
 				pos[0] = loc_pos[0] + m_Op_UPML->m_StartPos[0];
 				for (loc_pos[1]=0;loc_pos[1]<m_Op_UPML->m_numLines[1];++loc_pos[1])
 				{
@@ -303,8 +333,9 @@ void Engine_Ext_UPML::DoPreCurrentUpdates()
 		}
 	default:
 		{
-			for (loc_pos[0]=0;loc_pos[0]<m_Op_UPML->m_numLines[0];++loc_pos[0])
+			for (unsigned int lineX=0;lineX<m_numX.at(threadID);++lineX)
 			{
+				loc_pos[0]=lineX+m_start.at(threadID);
 				pos[0] = loc_pos[0] + m_Op_UPML->m_StartPos[0];
 				for (loc_pos[1]=0;loc_pos[1]<m_Op_UPML->m_numLines[1];++loc_pos[1])
 				{
@@ -331,10 +362,12 @@ void Engine_Ext_UPML::DoPreCurrentUpdates()
 	}
 }
 
-void Engine_Ext_UPML::DoPostCurrentUpdates()
+void Engine_Ext_UPML::DoPostCurrentUpdates(int threadID)
 {
 	if (m_Eng==NULL)
 		return;
+	if (threadID>=m_NrThreads)
+		return;
 
 	unsigned int pos[3];
 	unsigned int loc_pos[3];
@@ -343,8 +376,9 @@ void Engine_Ext_UPML::DoPostCurrentUpdates()
 	{
 	case Engine::BASIC:
 		{
-			for (loc_pos[0]=0;loc_pos[0]<m_Op_UPML->m_numLines[0];++loc_pos[0])
+			for (unsigned int lineX=0;lineX<m_numX.at(threadID);++lineX)
 			{
+				loc_pos[0]=lineX+m_start.at(threadID);
 				pos[0] = loc_pos[0] + m_Op_UPML->m_StartPos[0];
 				for (loc_pos[1]=0;loc_pos[1]<m_Op_UPML->m_numLines[1];++loc_pos[1])
 				{
@@ -369,8 +403,9 @@ void Engine_Ext_UPML::DoPostCurrentUpdates()
 	case Engine::SSE:
 		{
 			Engine_sse* eng_sse = (Engine_sse*) m_Eng;
-			for (loc_pos[0]=0;loc_pos[0]<m_Op_UPML->m_numLines[0];++loc_pos[0])
+			for (unsigned int lineX=0;lineX<m_numX.at(threadID);++lineX)
 			{
+				loc_pos[0]=lineX+m_start.at(threadID);
 				pos[0] = loc_pos[0] + m_Op_UPML->m_StartPos[0];
 				for (loc_pos[1]=0;loc_pos[1]<m_Op_UPML->m_numLines[1];++loc_pos[1])
 				{
@@ -394,8 +429,9 @@ void Engine_Ext_UPML::DoPostCurrentUpdates()
 		}
 	default:
 		{
-			for (loc_pos[0]=0;loc_pos[0]<m_Op_UPML->m_numLines[0];++loc_pos[0])
+			for (unsigned int lineX=0;lineX<m_numX.at(threadID);++lineX)
 			{
+				loc_pos[0]=lineX+m_start.at(threadID);
 				pos[0] = loc_pos[0] + m_Op_UPML->m_StartPos[0];
 				for (loc_pos[1]=0;loc_pos[1]<m_Op_UPML->m_numLines[1];++loc_pos[1])
 				{
diff --git a/FDTD/engine_ext_upml.h b/FDTD/engine_ext_upml.h
index ea0a278..5cdc0f5 100644
--- a/FDTD/engine_ext_upml.h
+++ b/FDTD/engine_ext_upml.h
@@ -30,15 +30,24 @@ public:
 	Engine_Ext_UPML(Operator_Ext_UPML* op_ext);
 	virtual ~Engine_Ext_UPML();
 
-	virtual void DoPreVoltageUpdates();
-	virtual void DoPostVoltageUpdates();
+	virtual void SetNumberOfThreads(int nrThread);
 
-	virtual void DoPreCurrentUpdates();
-	virtual void DoPostCurrentUpdates();
+	virtual void DoPreVoltageUpdates() {Engine_Ext_UPML::DoPreVoltageUpdates(0);};
+	virtual void DoPreVoltageUpdates(int threadID);
+	virtual void DoPostVoltageUpdates() {Engine_Ext_UPML::DoPostVoltageUpdates(0);};
+	virtual void DoPostVoltageUpdates(int threadID);
+
+	virtual void DoPreCurrentUpdates() {Engine_Ext_UPML::DoPreCurrentUpdates(0);};
+	virtual void DoPreCurrentUpdates(int threadID);
+	virtual void DoPostCurrentUpdates() {Engine_Ext_UPML::DoPostCurrentUpdates(0);};
+	virtual void DoPostCurrentUpdates(int threadID);
 
 protected:
 	Operator_Ext_UPML* m_Op_UPML;
 
+	vector<unsigned int> m_start;
+	vector<unsigned int> m_numX;
+
 	FDTD_FLOAT**** volt;
 	FDTD_FLOAT**** curr;
 	FDTD_FLOAT**** volt_flux;
diff --git a/FDTD/engine_extension.cpp b/FDTD/engine_extension.cpp
index 216a170..242d28c 100644
--- a/FDTD/engine_extension.cpp
+++ b/FDTD/engine_extension.cpp
@@ -24,12 +24,62 @@ Engine_Extension::Engine_Extension(Operator_Extension* op_ext)
 	m_Op_ext = op_ext;
 	m_Eng = NULL;
 	m_Priority = 0;
+	m_NrThreads = 1;
 }
 
 Engine_Extension::~Engine_Extension()
 {
 }
 
+void Engine_Extension::SetNumberOfThreads(int nrThread)
+{
+	if (nrThread<1)
+		return;
+	m_NrThreads=nrThread;
+}
+
+void Engine_Extension::DoPreVoltageUpdates(int threadID)
+{
+	//if this method gets called the derived extension obviously doesn't support multithrading, calling non-MT method...
+	if (threadID==0)
+		DoPreVoltageUpdates();
+}
+
+void Engine_Extension::DoPostVoltageUpdates(int threadID)
+{
+	//if this method gets called the derived extension obviously doesn't support multithrading, calling non-MT method...
+	if (threadID==0)
+		DoPostVoltageUpdates();
+}
+
+void Engine_Extension::Apply2Voltages(int threadID)
+{
+	//if this method gets called the derived extension obviously doesn't support multithrading, calling non-MT method...
+	if (threadID==0)
+		Apply2Voltages();
+}
+
+void Engine_Extension::DoPreCurrentUpdates(int threadID)
+{
+	//if this method gets called the derived extension obviously doesn't support multithrading, calling non-MT method...
+	if (threadID==0)
+		DoPreCurrentUpdates();
+}
+
+void Engine_Extension::DoPostCurrentUpdates(int threadID)
+{
+	//if this method gets called the derived extension obviously doesn't support multithrading, calling non-MT method...
+	if (threadID==0)
+		DoPostCurrentUpdates();
+}
+
+void Engine_Extension::Apply2Current(int threadID)
+{
+	//if this method gets called the derived extension obviously doesn't support multithrading, calling non-MT method...
+	if (threadID==0)
+		Apply2Current();
+}
+
 bool Engine_Extension::operator< (const Engine_Extension& other)
 {
 	return (GetPriority()<other.GetPriority());
diff --git a/FDTD/engine_extension.h b/FDTD/engine_extension.h
index 9dcac7b..aa2342c 100644
--- a/FDTD/engine_extension.h
+++ b/FDTD/engine_extension.h
@@ -27,19 +27,27 @@ class Engine_Extension
 public:
 	virtual ~Engine_Extension();
 
+	virtual void SetNumberOfThreads(int nrThread);
+
 	//! This methode will be called __before__ the main engine does the usual voltage updates. This methode may __not__ change the engine voltages!!!
 	virtual void DoPreVoltageUpdates() {}
+	virtual void DoPreVoltageUpdates(int threadID);
 	//! This methode will be called __after__ the main engine does the usual voltage updates. This methode may __not__ change the engine voltages!!!
 	virtual void DoPostVoltageUpdates() {}
+	virtual void DoPostVoltageUpdates(int threadID);
 	//! This methode will be called __after__ all updates to the voltages and extensions and may add/set its results to the engine voltages, but may __not__ rely on the current value of the engine voltages!!!
 	virtual void Apply2Voltages() {}
+	virtual void Apply2Voltages(int threadID);
 
 	//! This methode will be called __before__ the main engine does the usual current updates. This methode may __not__ change the engine current!!!
 	virtual void DoPreCurrentUpdates() {}
+	virtual void DoPreCurrentUpdates(int threadID);
 	//! This methode will be called __after__ the main engine does the usual current updates. This methode may __not__ change the engine current!!!
 	virtual void DoPostCurrentUpdates() {}
+	virtual void DoPostCurrentUpdates(int threadID);
 	//! This methode will be called __after__ all updates to the current and extensions and may add/set its results to the engine current, but may __not__ rely on the current value of the engine current!!!
 	virtual void Apply2Current() {}
+	virtual void Apply2Current(int threadID);
 
 	//! Set the Engine to this extention. This will usually done automatically by Engine::AddExtension
 	virtual void SetEngine(Engine* eng) {m_Eng=eng;}
@@ -59,6 +67,8 @@ protected:
 	Engine* m_Eng;
 
 	int m_Priority;
+
+	int m_NrThreads;
 };
 
 #endif // ENGINE_EXTENSION_H
diff --git a/FDTD/engine_multithread.cpp b/FDTD/engine_multithread.cpp
index bac9207..fbd0c5a 100644
--- a/FDTD/engine_multithread.cpp
+++ b/FDTD/engine_multithread.cpp
@@ -48,14 +48,7 @@ Engine_Multithread::Engine_Multithread(const Operator_Multithread* op) : Engine_
 {
 	m_Op_MT = op;
 	m_type = SSE;
-	m_barrier_VoltUpdate = 0;
-	m_barrier_VoltExcite = 0;
-	m_barrier_PreVolt = 0;
-	m_barrier_PostVolt = 0;
-	m_barrier_CurrUpdate = 0;
-	m_barrier_CurrExcite = 0;
-	m_barrier_PreCurr = 0;
-	m_barrier_PostCurr = 0;
+	m_IterateBarrier = 0;
 	m_startBarrier = 0;
 	m_stopBarrier = 0;
 }
@@ -101,15 +94,7 @@ void Engine_Multithread::Init()
 	m_Op_MT->CalcStartStopLines( m_numThreads, m_Start_Lines, m_Stop_Lines );
 
 	cout << "Multithreaded engine using " << m_numThreads << " threads. Utilization: (";
-	m_barrier_VoltUpdate = new boost::barrier(m_numThreads); // numThread workers
-	m_barrier_VoltExcite = new boost::barrier(m_numThreads); // numThread workers
-	m_barrier_CurrUpdate = new boost::barrier(m_numThreads); // numThread workers
-	m_barrier_CurrExcite = new boost::barrier(m_numThreads); // numThread workers
-
-	m_barrier_PreVolt = new boost::barrier(m_numThreads); // numThread workers
-	m_barrier_PostVolt = new boost::barrier(m_numThreads); // numThread workers
-	m_barrier_PreCurr = new boost::barrier(m_numThreads); // numThread workers
-	m_barrier_PostCurr = new boost::barrier(m_numThreads); // numThread workers
+	m_IterateBarrier = new boost::barrier(m_numThreads); // numThread workers
 
 	m_startBarrier = new boost::barrier(m_numThreads+1); // numThread workers + 1 controller
 	m_stopBarrier = new boost::barrier(m_numThreads+1); // numThread workers + 1 controller
@@ -131,6 +116,9 @@ void Engine_Multithread::Init()
 		boost::thread *t = new boost::thread( NS_Engine_Multithread::thread(this,start,stop,stop_h,n) );
 		m_thread_group.add_thread( t );
 	}
+
+	for (size_t n=0;n<m_Eng_exts.size();++n)
+		m_Eng_exts.at(n)->SetNumberOfThreads(m_numThreads);
 }
 
 void Engine_Multithread::Reset()
@@ -146,14 +134,7 @@ void Engine_Multithread::Reset()
 		m_stopThreads = true;
 		m_stopBarrier->wait(); // wait for the threads to finish
 		m_thread_group.join_all(); // wait for termination
-		delete m_barrier_VoltUpdate; m_barrier_VoltUpdate = 0;
-		delete m_barrier_VoltExcite; m_barrier_VoltExcite = 0;
-		delete m_barrier_PreVolt; m_barrier_PreVolt = 0;
-		delete m_barrier_PostVolt; m_barrier_PostVolt = 0;
-		delete m_barrier_CurrUpdate; m_barrier_CurrUpdate = 0;
-		delete m_barrier_CurrExcite; m_barrier_CurrExcite = 0;
-		delete m_barrier_PreCurr; m_barrier_PreCurr = 0;
-		delete m_barrier_PostCurr; m_barrier_PostCurr = 0;
+		delete m_IterateBarrier; m_IterateBarrier = 0;
 		delete m_startBarrier; m_startBarrier = 0;
 		delete m_stopBarrier; m_stopBarrier = 0;
 	}
@@ -174,6 +155,67 @@ bool Engine_Multithread::IterateTS(unsigned int iterTS)
 	return true;
 }
 
+void Engine_Multithread::DoPreVoltageUpdates(int threadID)
+{
+	//execute extensions in reverse order -> highest priority gets access to the voltages last
+	for (int n=m_Eng_exts.size()-1;n>=0;--n)
+	{
+		m_Eng_exts.at(n)->DoPreVoltageUpdates(threadID);
+		m_IterateBarrier->wait();
+	}
+
+}
+
+void Engine_Multithread::DoPostVoltageUpdates(int threadID)
+{
+	//execute extensions in normal order -> highest priority gets access to the voltages first
+	for (size_t n=0;n<m_Eng_exts.size();++n)
+	{
+		m_Eng_exts.at(n)->DoPostVoltageUpdates(threadID);
+		m_IterateBarrier->wait();
+	}
+}
+
+void Engine_Multithread::Apply2Voltages(int threadID)
+{
+	//execute extensions in normal order -> highest priority gets access to the voltages first
+	for (size_t n=0;n<m_Eng_exts.size();++n)
+	{
+		m_Eng_exts.at(n)->Apply2Voltages(threadID);
+		m_IterateBarrier->wait();
+	}
+}
+
+void Engine_Multithread::DoPreCurrentUpdates(int threadID)
+{
+	//execute extensions in reverse order -> highest priority gets access to the currents last
+	for (int n=m_Eng_exts.size()-1;n>=0;--n)
+	{
+		m_Eng_exts.at(n)->DoPreCurrentUpdates(threadID);
+		m_IterateBarrier->wait();
+	}
+}
+
+void Engine_Multithread::DoPostCurrentUpdates(int threadID)
+{
+	//execute extensions in normal order -> highest priority gets access to the currents first
+	for (size_t n=0;n<m_Eng_exts.size();++n)
+	{
+		m_Eng_exts.at(n)->DoPostCurrentUpdates(threadID);
+		m_IterateBarrier->wait();
+	}
+}
+
+void Engine_Multithread::Apply2Current(int threadID)
+{
+	//execute extensions in normal order -> highest priority gets access to the currents first
+	for (size_t n=0;n<m_Eng_exts.size();++n)
+	{
+		m_Eng_exts.at(n)->Apply2Current(threadID);
+		m_IterateBarrier->wait();
+	}
+}
+
 //
 // *************************************************************************************************************************
 //
@@ -205,10 +247,7 @@ void thread::operator()()
 		for (unsigned int iter=0;iter<m_enginePtr->m_iterTS;++iter)
 		{
 			// pre voltage stuff...
-			if (m_threadID==0)
-				m_enginePtr->DoPreVoltageUpdates();
-
-			m_enginePtr->m_barrier_PreVolt->wait();
+			m_enginePtr->DoPreVoltageUpdates(m_threadID);
 
 			//voltage updates
 			m_enginePtr->UpdateVoltages(m_start,m_stop-m_start+1);
@@ -217,56 +256,46 @@ void thread::operator()()
 			DEBUG_TIME( m_enginePtr->m_timer_list[boost::this_thread::get_id()].push_back( timer1.elapsed() ); )
 
 			//cout << "Thread " << boost::this_thread::get_id() << " m_barrier1 waiting..." << endl;
-			m_enginePtr->m_barrier_VoltUpdate->wait();
+			m_enginePtr->m_IterateBarrier->wait();
 
 			// record time
 			DEBUG_TIME( m_enginePtr->m_timer_list[boost::this_thread::get_id()].push_back( timer1.elapsed() ); )
 
 			//post voltage stuff...
-			if (m_threadID==0)
-			{
-				m_enginePtr->DoPostVoltageUpdates();
-				m_enginePtr->Apply2Voltages();
-			}
-			m_enginePtr->m_barrier_PostVolt->wait();
+			m_enginePtr->DoPostVoltageUpdates(m_threadID);
+			m_enginePtr->Apply2Voltages(m_threadID);
 
 			// voltage excitation (E-field excite) by the first thread
 			if (m_threadID==0)
 				m_enginePtr->ApplyVoltageExcite();
-			m_enginePtr->m_barrier_VoltExcite->wait();
+			m_enginePtr->m_IterateBarrier->wait();
 			// voltage excitation finished
 
 			// record time
 			DEBUG_TIME( m_enginePtr->m_timer_list[boost::this_thread::get_id()].push_back( timer1.elapsed() ); )
 
 			//pre current stuff
-			if (m_threadID==0)
-				m_enginePtr->DoPreCurrentUpdates();
-			m_enginePtr->m_barrier_PreCurr->wait();
+			m_enginePtr->DoPreCurrentUpdates(m_threadID);
 
 			//current updates
 			m_enginePtr->UpdateCurrents(m_start,m_stop_h-m_start+1);
 
 			// record time
 			DEBUG_TIME( m_enginePtr->m_timer_list[boost::this_thread::get_id()].push_back( timer1.elapsed() ); )
-			m_enginePtr->m_barrier_CurrUpdate->wait();
+			m_enginePtr->m_IterateBarrier->wait();
 
 			// record time
 			DEBUG_TIME( m_enginePtr->m_timer_list[boost::this_thread::get_id()].push_back( timer1.elapsed() ); )
 
 			//post current stuff
-			if (m_threadID==0)
-			{
-				m_enginePtr->DoPostCurrentUpdates();
-				m_enginePtr->Apply2Current();
-			}
-			m_enginePtr->m_barrier_PostCurr->wait();
+			m_enginePtr->DoPostCurrentUpdates(m_threadID);
+			m_enginePtr->Apply2Current(m_threadID);
 
 			// current excitation (H-field excite) by the first thread
 			if (m_threadID==0)
 				m_enginePtr->ApplyCurrentExcite();
 
-			m_enginePtr->m_barrier_CurrExcite->wait();
+			m_enginePtr->m_IterateBarrier->wait();
 			// current excitation finished
 
 			if (m_threadID == 0)
diff --git a/FDTD/engine_multithread.h b/FDTD/engine_multithread.h
index 6831ee4..9662f4d 100644
--- a/FDTD/engine_multithread.h
+++ b/FDTD/engine_multithread.h
@@ -80,13 +80,20 @@ public:
 	//! Iterate \a iterTS number of timesteps
 	virtual bool IterateTS(unsigned int iterTS);
 
+	virtual void DoPreVoltageUpdates(int threadID);
+	virtual void DoPostVoltageUpdates(int threadID);
+	virtual void Apply2Voltages(int threadID);
+
+	virtual void DoPreCurrentUpdates(int threadID);
+	virtual void DoPostCurrentUpdates(int threadID);
+	virtual void Apply2Current(int threadID);
+
 protected:
 	Engine_Multithread(const Operator_Multithread* op);
 	const Operator_Multithread* m_Op_MT;
 	boost::thread_group m_thread_group;
 	boost::barrier *m_startBarrier, *m_stopBarrier;
-	boost::barrier *m_barrier_VoltUpdate, *m_barrier_VoltExcite, *m_barrier_PreVolt, *m_barrier_PostVolt;
-	boost::barrier *m_barrier_CurrUpdate, *m_barrier_CurrExcite, *m_barrier_PreCurr, *m_barrier_PostCurr;
+	boost::barrier *m_IterateBarrier;
 	volatile unsigned int m_iterTS;
 	unsigned int m_numThreads; //!< number of worker threads
 	volatile bool m_stopThreads;