Downpipe (SS) was tested and developed together with Evolution Line (Titanium) system.For the ultimate in weight reduction, tuning potential, and racing sound, Akrapovič offers stainless steel, cat-less downpipes to make the BMW an even more powerful machine. This setup is intended for dedicated track-day cars and enthusiasts, and it will also add to the overall experience of what’s already a stunning performance car for any discerning driver. Delivering great sound, without creating unwanted cabin noise, these beautifully-crafted downpipes offer an upgrade to Akrapovič’s Evolution exhaust system.When installing Akrapovič aftermarket optional down pipes , which are developed for use on closed tracks only, remapping the ECU is mandatory, in order to prevent potential »check engine light« warning signals.Downpipes also fit to M3/M4 CS (Sport Club) and GTS version.THIS PRODUCT DOES NOT MEET EMISSION COMPLIANCE REQUIREMENTS FOR STREET OR HIGHWAY USE.