COMP Cams Thumpr 275THR-9 Camshaft for LS Gen III/IV, Three-Bolt. Thumpr. High performance street, stock converter ok, best with 2000+ converter and gears, choppy/thumping idle. All COMP Cams Camshafts are manufactured to the strictest tolerances. Rigorously tested and checked for quality. Three unique cam designs for each application that deliver excellent horsepower gains & broad torque curve; perfect choice for muscle cars & street rods. Early intake valve opening & long exhaust duration create optimum overlap for powerful, hard-hitting exhaust note. Best with aftermarket converters & more rear gear.