If you want to go fast with predator, you need to talk to Pete or Chuck at Best Machine. They have the experience with these heads and know what they need. HP numbers only matter in a pissing contest. ET/MPH tell the real story. Have been 4.69@150 2350# p/s avenger. 612 N/A, glide with a conv that's still 200-300 tight. Std cam height and a less than desirable intake.