PART #SPD-5PX09-14-00: Designed to accommodate cams up to 9.3mm lift and up to 5500 rpm. Increases seat pressure by 20% over stock. PART #SPD-4WM09-14-02: Designed to accommodate cams up to 10.8mm lift and up to 5500 rpm. Increases seat pressure by 27% over stock. Includes new retainers to work with the increased cam lift.