I am installing an ATS exhaust manifold and BD turbo on my truck. Is it ok to gasket match the split volute opening on the turbo? The opening on the manifold outlet is a little larger than the turbo inlet, so there is going to be some major turbulence there I am afraid. I would hope matching it correctly would help keep drive pressures a little lower. I think I will be voiding my warranty on my new turbo though by grinding on it, what have others done?

EDIT: I went ahead and blended the inlet to the turbine. I measured the manifold outlet and turbine inlet and got:
manifold turbo
height 1.81 1.72
width 1.06 1.03

The width wasnt too bad, but the height was pretty bad. The stock manifold also was quite a bit smaller on the inlet side vs. the gasket. If the ATS manifold really does reduce drive pressure and EGTs it is probably because it has bigger tubes so it doesnt have as big of step for the gas to get around.