Just want to add to the comment on the FE performer RPM I built a 390 10.5:1 compression used the comp XE274 cam and edel performer rpm and I can not contain the rpm I hit the gas in 2nd gear (4spd manual in a 65 f100) and it is nothing to see 6500 - 7000 like yesterday. I do know that a factory C6AE-9425G intake for 390 and 428 has larger ports than the rpm but slightly shorter intake runners.
