S58 Crossover Pipe For BMW G80 M3, G82 M4, G83 M4The ARM S58 Crossover Pipe is designed to replace the restrictive factory S58 crossover pipe with a fully round design that improves exhaust flow. Unlike the OEM oval shaped pipe, the ARM crossover pipe maintains a consistent round shape, eliminating turbulence and flow restrictions caused by the factory design. Exotic exhaust sound Precision laser cut flanges Compatible with OEM and upgraded midpipes SS304 stainless steel construction 4 lbs lighter