The HSR45-5 Performance Carburetor Easy Kit is specifically designed as an upgrade kit for Harley-Davidson Big Twin and other American V-Twin engines using a modified exhaust, cam kit, performance, ignition, performance heads and possibly a big bore kit. The kit includes a 45-millimeter HSR Carburetor, Stock Airbox Adapter and instructions. The kit applications include Harley-Davidson 1999 to present Twin Cam, and 1990 to 1999 Big Twin Evolution models. The kit can also be used with some H-D Screamin’ Eagle higher flowing manifold kits that have HDSE part numbers 29634-00 (HTCC), or 29635-99 (TC), 29636-99 (Evo).