Looking for opinions /experience with aftermarket exhaust manifolds

[Longshot]

Does anyone have any experience or opinions on aftermarket exhaust manifolds like full tilt / Pittsburgh power?
Has Rawze, Unilevers or Mr Haggs ever done a custom tune with one of these manifolds installed?
If so, what were the results on boost / EGT, etc. compared to stock manifold?

http://{name removed}/cummins-08-11-egr/

If there is already a thread on this topic just point me in the right direction but I couldn't find one.

My truck is stock and still mandated.

Thanks
Longshot