I bought a manifold, supposed to be a rev hard B series A/C compatible manifold. Anyways, the hole for the wastegate measures 36.75mm. Does this mean I need a 36mm wastegate? Can you mount a 38mm wastegate without problems? Should I port the opening to 38mm?

 

Think about it... it is only .059" (roughly a 1/16th of an inch) off of 38mm... That opening will work with a 35mm or a 38mm waste gate... take your pick. The port is fine as is...

 

I thought more about it after I posted. The slight difference should have 0 effects. The wastegate opens by moving the piston up, which wouldn't matter how large the port is in terms of interfearance between the manifold/wastegate. Got it. Thanks.

 

Exactly.