Downpipe (Primary Catalyst Delete + Turbo Elbow) - Audi RS3 8V Pre FaceliftThe Primary Catalyst Bypass Pipe deletes the primary catalyst from the exhaust system. This part allows the exhaust gases to pass through the system unrestricted by the primary OE catalyst, increasing the gas flow and in turn engine efficiency. The Bypass Pipe comes equipped with a Turbo Elbow for fitment in vehicles possessing a turbo. The turbo elbow reduced back pressure allowing the turbo to Spool sooner reducing lag and improving throttle