Wagner Tuning 2 x 100 CPI Racing Cat PipesWagner Tuning 2 x 100 CPSI Racing Catalyst cat pipes for Audi TTRS and Audi RS3. Features: high quality stainless steel 1. 4301 (SS304) diameter 70mm with adapter for the original exhaust system 2 racing catalyst converter (100 Cells inch) better performance by reducing back pressure, significantly higher torque plug and play for Audi TTRS 8J and Audi RS3 8P compatible with the original downpipe or Wagner Tuning downpipe