I guess I will have to go against the grain a little, all flow benches dont share the same numbers. I had a pair of SS heads sent to me to "check out" for a friend, supposed to flow 320 c.f.m. they flowed 290 on my S.F.600, the same heads I did for Dave Mann flowed 303 c.f.m. 440 six pack super stock heads. I know for a fact If the other heads flowed 303 the car would not go any faster, possibly slower if the "shape" got screwd up trying to get the big number. Shape and port volume is what works, at least from my testing...