MAPerformance doesn't port intake manifolds any more, so how do I do the porting myself? I don't have a way to flow test each port, so I think my best choice is to smooth out all the deep imperfections and gasket match port both ends. I'll probably start next week after some research. Thanks for any help or links.

Thinking more about this, I'll fully match port with the throttle body gasket. But on the head intake, I will port to slightly smaller than my factory head intake. Since my head is not ported, it doesn't make sense to port that part on the intake manifold. The opening port before the gasket should not be bigger than the port after the gasket.

I would like to learn how to do this myself too. Thanks for the post

We still offer a porting service for the stock intake manifolds. Even with cheap tools and abrasives youre stil gonna be more than halfway to just getting the manifold ported by a shop. If its something you plan to do more than once it might be worth it to invest in the tools, otherwise let someone do it that has the tools already.

-Austin@STM

Thanks Austin. I agree with getting it done by machine shop. Unfortunately, my head still has not been touched and won't be for another 60k miles. I think opening up the runners will cause more problems unless I get my head ported as well. How much larger are your ports vs stock intake ports on head?

Buschur's thread about flow rates is very interesting. Is it possible cylinder #4 gets most of the air flows because the throttle body butterfly valve diverts air down first when we floor the gas pedal? It starts the flow downward so flows continue downward?

Check out the fluid dynamics of throttle body (butterfly valve). Looks like pressure build on top, seeps behind plate, and follow plate into cylinder #4 first. Very interesting!

Double post. These updates are screwing me up. Lol