My 526 C.I. 440 stroker motor made 775 HP at 6500 RPM and the same at 7000 RPM with the SR heads I mentioned, they have a set of 1.65 T&D single shaft rockers. The same motor with the CNC ported set of 440-1 withh Harland Sharp 1.65 rocker made 845 HP at 7000 RPM with no other changes and the 440-1 have a really big exhaust port that ended up making the motor miss from 5200 RPM up because the dyno headers are to small to fit the 440-1 heads properly There may have been a little bit more power left on the table because of that That motor will have a set of custom made headers in the race car, 2 .125 stepped up to 2.25 with 4 inch collectors instead of a set of 2.0 inch primarys with 3.5 collectors, the flanges will be bigger than the exhaust ports with no over hang over the heads ports Not like the dyno headers