The factory exhaust system on the 2005-up Mustang GT flows well in stock form. When upgrading engine components with throttle bodies, programmers, headers, forced induction and etc. the demand for a un-restrictive exhaust increase. We have combined Ford Racing's stainless steel X-Pipe with their Exhaust kit to offer a free-flowing exhaust that will increase performance and give you a louder, throatier exhaust note.