BMW GENUINE M PERFORMANCE SILENCER SYSTEM. 18 30 5 A23 283. This listing is for the BMW M Performance Silencer System. This includes the Exhaust system 18.30.5. A23.283, Titanium Finisher 18.30.5. A23.286, Carbon Rear Diffuser 51.95.5. A19.8B5 and 4 Tailpipe Trims in a Black Finish 18.30.5. (The Images are for illustrative purposes only and