ACTIVE AUTOWERKE E9X M3 SIGNATURE REAR EXHAUST GEN. 2True performance, durability, and attractive weight advantages with innovative features places the Active Autowerke E9X BMW M3 exhaust in a class of its own. This system is constructed from 100% 304 stainless steel and features adjustable Active Autowerke double walled tips, making it ideal both for 2 door and 4 door models (also allows for cleaner fitment with diffusers). This system uses factory style flanges making it a complete bolt on system that