Looking for opinions /experience with aftermarket exhaust manifolds

[Rawze]

I did not say what I did because it was speculation. I have met many like marek4792 who have had them.

I even met a guy who did some measurements both before and after using his manifold temp gauge. Heat absorption seemed to be about the same. Here is why...

The biggest exhaust restriction in a turbocharged diesel engine BY FAR, and first and foremost IS THE TURBOCHARGER ITSELF, far exceeding the other components like the exhaust manifold. It absorbs a ton of heat and makes the exhaust gases slow down significantly in the manifold itself. The gas being slowed down in the manifold causes it to absorb more heat too,.. it does not matter what sort of coating or polishing it has because of this until you start moving more volume through it than it can stand,.. and that is not likely to happen because the turbocharger is holding as much as 90-PSI of exhaust back-pressure under full operating load.

Think about it --- As much as NINETY+ PSI of back-pressure to make 36-38 psi in the intake is not unusual.

there are things you can do to help efficiency, but replacing the exhaust manifold is not one of them unless your exceeding its flow capacity, ands the factory manifolds capacity is above the 600HP rating of the engine. What WILL help, is reducing the heat that escapes, trapping it in the system as much as possible. This means that an exhaust wrap will in fact start to create a measurable difference because less heat is absorbed and bled off in the components.

That is what I know about it,.. of course,. I am full of s#it.