Get faster, smoother throttle response where you need it most. Installed in your throttle body's venturi tube, the precision-engineered sleeve reduces the diameter and accelerates the velocity of your air-fuel mix. Add the thinner butterfly valve and less obstructive shaft, and you've got faster, more even throttle response through low- and mid-range. For better top-end throttle response (90 - 100% open throttle position), use the kit's larger butterfly valve without the sleeve. Either way, you can: Get faster, smoother throttle response. Eliminate high-end flow loss by lowering flow restriction. Install / remove without damaging the O.E.M. throttle body. Count on maintenance-free reliability after installation. "Downsizing the throttle increased (air) velocity - which pays dividends in the low-to-mid range." - Motocross Action.