Ok, so I have been using these ProComp SBM heads for about 1 1/2 years now. I think I got a pretty good handle on them. As with any head or part, they could use a bit of massaging to make them work real good. So here is our latest attempt. Im going out on a limb here and going to claim the MOST POWER MADE TO DATE WITH THESE HEADS, N/A NO FORCED INDUCTION, NO NOS! This is a re-do from an engine we built last year. Customer wanted more power so we pushed it up a bit. here is the run down. 360 magnum R block 4.060 bore 3.825 stroke 6.250 rod From the top down......... 1050 Dominator Super Victor, ported in house T&D roller rockers Procomp heads, flowing 312/230 Custom Ractec flat top pistons 12.2 to 1 Custom Lunati roller cam, sorry no specs. I can tell you high 270's and mid .600's MRL Pro PLUS soild roller lifters 3/8 pushrods PEP I beam rods HP bearings Billet timing set w/tensioner Mallory 32 series dist 34* total Custom made wires Champion plugs Kevko oil pan Melling HV oil pump Bla bla bla Now for the fun stuff. Torque, its whats for dinner. It peaked at 564TQ at 5400rpm. But it had 530 from 4600-6650. Hell at 7200 it still had 475TQ!!!!! HP, its what kills the Chevys. Peak was 670HP 6550rpm. It made 600+ from 5600rpm on up. Still making 650HP at 7200rpm. BSFC was .395-.459 the entire run and still had a A/F ratio of 11.3-11.9. I wanted to tune more but ran out of dyno time. Valve lash was best at .025I .026E. Ran a 2" tapered spacer fro the Dominator. So there you have it 670HP with a 396ci SBM and those damn ProComp heads. BTW they are out of stock and will not have any until November.