The Primary Catalyst Bypass Pipe removes the primary catalyst from the exhaust system. This component allows exhaust gases to flow through the system without restriction from the original equipment catalyst, increasing gas flow and engine efficiency. The Bypass Pipe includes a Turbo Elbow for vehicles equipped with a turbocharger. The turbo elbow reduces back pressure, enabling the turbo to spool sooner, which decreases lag and improves throttle response. Note: Requires Stage 2 ECU remap. - Deletes the primary catalyst for increased exhaust flow - Includes Turbo Elbow for turbocharged vehicles - Reduces turbo lag and improves throttle response Specifications: - Pipe Diameter: 76.20 - Race Product: Yes - EMarked: No Kit comes with: - 100mm Hi-Flow Turbo Elbow - MSAU679 - Catalyst Bypass Pipe - MSAU680REP Vehicle Compatibility: - Audi RS3 Sportback (8V MQB - Pre Facelift Only) 2015-2017