The stock x-pipe on BMW E9X M3, with its primary and secondary pairs of catalytic converters, is the most restrictive component of the exhaust system. The Macht Schnell Stainless Steel Race X-Pipe is a complete replacement and features a high-flow resonated design for maximum power gains and optimal sound. Replacement gaskets and hardware are included for 100% reversible bolt-on installation that accepts most axle-back exhausts.