Oh ok, thanks alot for the info. So then I think I will just buy the vafc for now, but later on add the throttle body first followed by working on the head. Another question I have Jasma headers and a Apexi WS 2 on a stock cat. I wanna get either a testpipe or high-flow cat, any suggestions on which one and what size 2 1/4 or 2 1/2?