I guess you're right. I've run iron '906 heads at 11.9:1 on 91 octane for maximum horsepower and never been able to make any more than 748 HP at our home dyno. I thought we were gonna make more on Comp Cams dyno, but the dyno operator forgot to turn the water on to the engine and we had to run a blown up engine, with bent valves and 56% leakdown, that only made 730 HP there.
