On a stock set of heads, stock displacement, and along with the mods in my signature...if i port matched the intake would a 58mm throttle body really make any difference in performance at all? Slight HP increase, maybe just a better throttle response? I was just curious, that would end up being my next little bolt on if i see it as worth it, when i go to a 383 setup, i know im going to need it but for now i just wanted some insight on it as to whether or not it would make any real difference. Thanks for ur time

 

You will get the feeling of better throttle response from the "tip in" of the larger blades, but there will not be much of a power increase - a stock headed, stock cube LT1 cannot move enough air to warrant a 58mm TB unless you spin it to impossible RPMs. At 6500 rpms a 350ci engine can only possibly move around 660cfm of air - well under the 1,000 or so CFM of most 58mm TB's, and much closer to the ~750 cfm of a 52mm unit.

Also, you will have to deal with things like idle tuning(maybe having to drill out IAC passage and/or seclude it), resetting TPS sensor, and a possibility of shifting problems on autos due to the vehicle being at different speeds per throttle percent vs the stocker.

For stock/bolt on LT1s 52mm is a nice upgrade from stock without a lot of the hassle from a 58mm piece.