This downpipe adapter for the 2002-2014 WRX & STi is the perfect solution to the problem of matching an 3-inch aftermarket downpipe to a catback system that uses the stock 2.5in taper. The 3-inch downpipe adapter plate allows you to install the factory donut gasket on the end of any 3-inch flat flange downpipe, to ensure a perfect seal with the factory or any other 2.5in tapered catback exhaust system (Cobb Tuning, Blitz, Borla & Greddy just to name a few).
Now you can bolt up virtually any downpipe/catback combination on the market without having to worry about exhaust leaks or installation nightmares. The 3-inch downpipe adapter requires a flat flange gasket as well as an OEM donut gasket for proper seal. Because this will modify your downpipe, longer downpipe bolts may be necessary.