This is the Silent Muffler for the following SuperTigre engines: S2000, S2500, S3000, S300K, G3250, and the G4500 (see note below for this engine!) It is a direct replacement for the old swing muffler and features a decrease in noise, while modestly increasing performance of the engine. INCLUDES: One Silent muffler One Exhaust stack One Exhaust gasket One Pressure tap w/gasket One 4x22mm machine screw One 4mm nut Two 4x14mm muffler screws Three 4mm lock washers SPECS: Length of muffler: 185mm (7¼") Distance between screw hole centers: 45mm (1¾") COMMENTS: If using this muffler on the G4500, customer MUST also purchase the SUPG1631 exhaust stack (header). ir/jl