Our Subaru Impreza Decat Downpipe replaces the standard restrictive downpipe and catalytic converters with a stainless steel, one-piece item. Increasing the bore of the downpipe and replacing the restrictive catalytic converters allows the exhaust gasses to flow much more freely, increasing the power output of the engine. Features: Manufactured from T304 stainless steel 3" bore throughout TIG welded, CNC machined flanges Boss fitted to accept O2 (lambda) sensor Sleek, polished finish Fitment: Subaru Impreza GDA New Age WRX STi 2002-2007 models Please note: this item may not comply with your local emissions regulations so is sold for off-road/track use only.