Akrapovic BMW M340i & M440i Exhaust Sound Kit (G20, G21, G22, G23 & G26)The optional Akrapovi Sound Kit enables BMW M340i & M440i owners with Akrapovi exhausts to switch between the quiet mode and a sportier sound. With the use of a receiver to drive the actuators that open or close the valves at the end of the exhaust system, drivers can use the Sound Remote Controller or the new smartphone app (for iOS and Android) to regulate the valves. With the use of the optional Akrapovi Sound Kit, the ECE type approval is no