Dr. Pulley Clutch for Yamaha Zuma 125 enables high contact pressure, not only through centrifugal force, but using a double wedge system. They include the regular clutch spring and newly designed pillow spring, which will give you more power to the ground. The stronger your engine the more response the Dr. Pulley clutch will achieve.  Most clutches can give you a fast take off out of the hole but will start slipping at higher revs, but the HiT clutch actually delivers more power on inclines or when accelerating.  Most Dr. Pulley Clutch delivers up to 30% more power to the ground and faster response.