2015-20 Ford Mustang Ecoboost Downpipe - Increase performance and improve sound with our Ford Mustang Ecoboost Downpipe. Our 2015 Mustang downpipe is designed with a 3" diameter catted lead pipe. This 304 stainless steel downpipe is TIG welded and fits to the SW Ecoboost Mustang exhaust. Get superior performance with a lifetime guarantee with Stainless Works.