Hi Dick, I\'ve been using a set of PROFORMS true rollers. I cranked my sbc to 7,200rps all the time. True rollers cut down on drag in the valve-train. Mainly where the pushrod and rocker meet. You do have to get taller valve covers though. I\'ve broke a few stockers and no rollers. If you plan on high rpm\'s, buy them up. If you gonna putz around it throwing $$$ away.