I too am building a bbc motor replacement bullet for my daily driver and have looked at the Comp Cam line. This site (namely the two individuals above) have convinced me to use a hydraulic roller cam. I have the Comp Cam simulator loaded on my computer. The 601 Thumper is a 291 duration cam that makes 437 hp and 480 torque in my application. The 290 Magnum cam makes 497 hp and 516 torque. That is giving away alot of ponies for sound. Plus the Thumper cam cost more! Two negatives!!