Because of packaging requirements, the EVO system has been split into two codes. Please be aware that both part numbers (MTP-ME/T/2H/1 or MTP-ME/T/3H and E-ME/T/3) must be ordered.If the Akrapovič Evolution Line system replaces the Mercedes-AMG performance exhaust system, the Valve Actuator Kit (P-HF985) is not needed. The valves on the exhaust can be controlled from the car cabin. The Akrapovič Sound Kit (P-HF949) can be purchased as an optional part.If the car is not equipped with a performance exhaust but with the basic Mercedes-AMG exhaust system, then the Valve Actuator Kit (P-HF985) is mandatory. The Akrapovič Sound Kit (P-HF949) is also highly recommended for complete control over exhaust sound regulation.