I'm curious about Brian's answer also. But are we still talking about EQ heads or the RHS/IndyX head that Brian was running? Because, with the same head casting that Brian was using I know that at least 629 HP is possible. We did that with 2.5 points of compression less, 10 degrees less cam and .050" less lift.........on 91 octane pump gas! If you want to run that LAX/MAX head, I'm sure you can get well over 600 HP. I've work with them both now, and they are not the same head!