Camaro/Firebird 1992-'97 LT-1 Throttle Body 58mm Polished Professional Products throttle bodies are precision engineered and many of them are made of alumnium die casting which is the same process used by the original equipment manufactures. Those that are not die cast are made from permanent mold castings, a superior casting process to the sand casting used by all other aftermarket throttle body manufactures making cast throttle bodies. Additionally, not only is the Professional Products Power line of throttle bodies the best quality, they are also the least expensive