[Rickd]

The AFR's make power, that is proven. As far as how sturdy the stock assemblies are for serious racing, I could not answer that, but I do know that people who use them for serious racing generally change the springs and valves. They try to buy the castings, and then add high end components, as the castings are very good and the CNC air flow on the AFR's is very good. My 331 stroker with AFR 165's dyno'd 446 hp at 6000 rpm on the stand, and after installation, gave 326 rwhp on a chassis dyno tuner. Power is there, but this motor has the stock valves etc. If it were going in a race car I would have bought bare castings, added real nice valves, studs, springs, and a girdle. Rickd