RENNtech EVM | Exhaust Valve Module | 222 - S 550 Sedan and 217 - S 550 CoupeRENNtech Exhaust Valve Module Permanently Open Exhaust Flaps. 222 S 550 Sedan and 217 S 550 Coupe EVM Exhaust Valve Module (Remote Controlled) NOT SO FUN FACT: If your Mercedes AMG is equipped with factory exhaust valves, with or without a center console button to open or close them, factory settings do NOT allow the flaps to fully open unless certain speed and or RPM have been reached. For example, while cruising the exhaust flaps will never fully