2008-2014 WRX / 2008-2021 STI Invidia Down Pipe w/High Flow Cat and Extra 02 Bung For a strong boost in power, the Invidia Down Pipe offers an alternative to other power-boosting enhancements. To see just how much power the Invidia Downpipe can produce, a quick look at its dyno chart shows it easily added several horsepower to the stock exhaust system. Each Invidia Downpipe features a large 4" Stainless Steel bellmouth to enhance power by freeing excess gas.  In addition, each Invidia Downpipe can be bolted up to any Invidia Exhaust or a stock exhaust for an easy installation. Features 4" 304 Stainless Steel bellmouth 3" 304 Stainless Steel piping Divorced wastegate bellmouth Benefits Can be bolted up to any Invidia Exhaust or a stock exhaust for an easy installation. Enhances power by freeing excess gas. Easily added several horsepower to the stock exhaust system. Applications 2008-2014 Subaru Impreza WRX 2008-2021 Subaru Impreza WRX STI 2005-2009 Subaru Legacy GT (manual) 2009-2013 Subaru Forester XT 2005-2009 Subaru Outback XT What's in the box? Invidia Bell Mouth Downpipe Necessary Hardware Installation Warranty 1 Year Manufacturers Warranty