Active Autowerke F3X 335i | 435i Performance Valved Rear Exhaust GEN 2True BMW performance, durability, and attractive weight advantages with innovative features places the Active Autowerke BMW F3x 335i exhaust in a class of its own. And now Active Autowerke has developed Gen 2 of this model which has been enhanced to take advantage of the OEM valve system. This system is constructed from 100% Brushed 304 stainless steel and features adjustable brushed, black or carbon Active Autowerke double walled tips, making it