Our Power Filter feeds your Yamaha HO engine a steady diet of cool air delivering greatly improved acceleration and rpm. Replaces restrictive stock air box with a high-volume, K&N filter element that is attached to throttle body via a precision machined velocity stack. Also features an easy to install Engine Breather Upgrade Kit that eliminates power-robbing crankcase emissions from your engine’s air intake. Power Filter Kit includes water-repellent pre-filter and detailed installation instructions.