Heavy clutch lever effort at higher RPM that limits the amount of centrifugal clamping that can be applied is what all regular clutch lock up systems have vance and hines exhaust. Vance and Hines clutch repair kit is designed to start limiting the pressure at about 3500RPM(adjustable),vance and hines harley the maximum engine torque, and it provides much stronger clutch performance and a really controllable clutch. The constant force mode can be disabled for maximum pressure