Our 58MM throttle bodies start out as a solid chunk of 6061 T6 heat treated aluminum (not a casting). They feature a re-designed throttle linkage cam for better throttle control and feel. They also sport a black oxide finished-turned, ground and polished throttle shaft supported by sealed ball bearings for a super long lifespan, and CNC machined throttle blades (not stamped like others) for a precise fit. Bodies are anodized 'Carbon Black' for a long lasting finish. A billet IAC housing, TPiS ID plate, and gaskets are included. All parts are manufactured by TPiS in the U.S.A. This throttle body flows nearly 1100cfm and are great for engines making 450-550hp.