darin is correct for the most part,, but what he said and what i said arent the same,, read it again,, i never said the intake ports go sonic,, exh ports can,, beacuse of the pressures in the cylinder when the exh valve is initially opened.. the intake port cross section will just limit how high the engine will peak at,, everybody knows that....... and pro stock trucks used w-9 heads when they were slow,, they used p-5 heads when they were fast,, also,, a "good" pro stock truck w-9 flowed just about 390-400,, which is enough to make 950hp,, he is claiming 470,,, see my point yet???

also,, i have a cnc machine,, and computer software for it,, i can see the ports on my computer screen and slice them wherever i want,, not use calipers and guess,,, plus like i said,, ive worked on engines along with others,, and witnessed peak power at a predicted rpm based on minimum int cross section and runner length