I just finished the dyno time with my 447 SB2.2, it made 801.4HP at 6600, 829.7 peak at 7500, 805.6 at 8000, and still 796.8 at 8200 where we quit. These heads flowed 398 @ .800 lift on intake. I am hoping Bill will know where to get some better ones for the 9.5 deck 460 we want to start on this summer...