Improves starting, ridability, power ADN torque Features a two piece throttle slide that rolls on stainless roller bearings, a lighter throttle return spring, a low speed air screw and an enlarged needle valve and float bowl Kits include HSR42 carburetor, performance intake manifold, free flowing K&N air filter assembly, chrome air cleaner cover, adaptors and detailed installation and tuning manual Fits all carbureted Twin Cam models