AIRTEC Motorsport Downpipe for Mk3 Focus RSBy using this test pipe, back pressure is hugely reduced, which effectively improves the engines breathing by allowing it to expel gases more quickly. This in return means faster throttle response, increased power output and a more aggressive exhaust note. With a new bore size of 70mm the new AS performance Replacement Down Pipe has over 50% more capacity. NOTICE: This is for off road use or track use ONLY. Not legal for on road use in a pollution