I have yet to see a desk top program match real world results Maybe I shouldn't buy or use cheap desk top programs Maybe no two computers and dynos are identicle I had two 440 motors with identicle bore and stroke motors,4.38 bore and 3.75 stroke. Motor #1 was 14.7 to one compression with a set of B1-BS heads with 440 port sizes and a Crane custom ground solid roller that was 274@.050 ground on 106 LSA in at 105, BME aluminum rods, it made 627 HP. Motor #2 was 12.8 to 1 comp. ratio with a set of ported 906 heads with 2.14 intake valves and 1.81 exhaust valves, these heads flowed 14 CFM less than the B1-BS heads did on the same Super Flow 600 bench, the cam was a Cam Dynamics R282 solid roller ground on 108 LSA installed at 106 ILC, that motor made 625 HP on the same DTS dyno six months later Both motors had the same type intake, M1 4500 and the same Dominator carburetor, Holley 1050 CFM List # 9375 , motor #1 and #2 both used C12 race fuel, two different batches 6 months apart