The Akrapovič Sound Kit allows the driver to easily adjust the sound of the exhaust from inside the car’s cockpit. Using the latest innovative technology and working with the car’s own electronics, the Akrapovič Sound Kit provides different sound characteristics through the control of the active X-connection built into this superb Evolution Line (Titanium) system.For a car equipped with the base Mercedes-AMG exhaust system – with no exhaust system button inside the cabin – the Akrapovič Sound Kit (P-HF949) is a highly recommended upgrade to take complete control over the exhaust sounds.If the car is already equipped with exhaust valve button inside the cabin, sound kit is not needed.Pictures are symbolic.