Akrapovic 16-17 BMW M2 (F87) Sound Kit
The sound of the superb Evolution Line (Titanium) exhaust system can be further controlled by adding the optional Akrapovič Sound Kit. This easy-to-install option makes possible louder or quieter settings of the Evolution Line. It has a special program for valve management (in quiet and loud mode) that is different from the stock version and controls the valves according to rpm, gear, and car mode.
Pictures are symbolic.