Designed to perfectly match the power band of their Performer RPM Series of intake manifolds. Tested and tuned on engine dynamometers for maximum performance. Offers improved throttle response and torque. Intake Valve Lift With Factory Rocker Arm Ratio is 0. 560 and exhaust valve lift is 0. 573. Intake durationat0. 050 inch lift is 240 and the exhaust duration is 247