I was measuring my b16 throttle body on my p30 manifold during the recent wire tuck I did. It was only 58mm. I was wanting to to pick up a skunk2 alpha throttle body and was curious about how large the stock manifold can be ported to. I was looking at 66mm instead of the 70mm throttle body.

Motor is b16a2, cai, megan 4-1 header, 2.5 inch collector and exhaust & SIR2 cams. I plan on staying na.

Any advice?