You are really being generous on horsepower for a head that flows around 275 cfm max out of the box at 700-750 lift. How big a cam is he going with. 650 at most I would bet, probably lower. Then subtract .035 for lash and pushrod deflection what are those heads flowing now at his lift. Now add in how much he will lose with an out of the box intake. Hmmmm 600 horsepower, I don’t think so.
