- Mar 31, 2005
I recently purchased an evo iii gt exhaust manifold that someone had started porting (matching to an oem gasket). Just a few weeks ago i had the porting job finished by a local machine shop. Once i removed my stock turbo & manifold I realized that the ports on the head are now smaller in diameter than the ports on the gt manifold. I've done some searching on here and found that porting the exhaust side on the head is really pointless but im wondering if i assemble w/o porting the head will the step up in size create any turbulance which could hurt flow/spool to the turbo?