Akrapovic Sound Kit for BMW X5M / X6M (F85, F86)OP Optional partThis easy to use optional extra gives the driver the opportunity to switch between dual mode settings for either a sporty sound between the deeper and higher frequencies, or the more regular Akrapovi sound. It works by fully controlling the opening and closing of the exhaust valves simply by pushing a button on the Sound Remote Controller or via the downloadable app. Pictures are symbolic. PERFORMANCE: Unit Stock Akrapovic Max gain