Akrapovic brings another great product to BMW enthusiasts. These high quality catless downpipes replace factory catted downpipes while delivering more power to your vehicle. This product is intended for off-road use only. When installing Akrapovic’s aftermarket optional downpipes without catalytic converters, remapping of the ECU is mandatory. When downpipes are used in conjunction with the Evolution System, this is virtually the same setup that is used on the 1M Moto GP Safety Car. The high-flow downpipes do require ECU reprogramming to eliminate the check engine light and for peak power output. They are only for the dedicated track day car or hardcore enthusiasts.