The optional Akrapovič Sound Kit enables owners of selected Akrapovič car exhausts to control the sound of the system from the cockpit of their machine. Using Akrapovič technology, drivers can easily 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. If stock system has exhaust valves integrated (Porsche sport exhaust) no wireless kit is needed.Pictures are symbolic.