Also fits Shelby GT and GT500 models. American Thunder Kit Cat back, Exhaust, Kit, Mustang, GT, Stainless, Performance Cat-back 409S 05-10 Mustang Cat-back System 409S - Dual Rear Exit - American Thunder - Aggressive Sound Cat-back System 409S - Dual Rear Exit - American Thunder - Aggressive Sound - 2005 to 2010 Ford Mustang GT and GT500 Exhaust System Kit Fits 2005 to 2010 Ford Mustang GT and GT500 and California Special and Convertible with a 4.6L or 5.4L engine. For the serious enthusiast who is looking for all the performance benefits of a complete Cat-back dual exhaust system, this is it. As an American Thunder system, it delivers an aggressive exterior sound level and a moderate interior tone that is suited to the enthusiast who wants to be heard. With maximum performance and easy fit in mind, the system is mandrel bent and includes specially engineered mufflers featuring Delta Flow technology. Like all Flowmaster systems, the benefits include improved throttle response, power and mileage. Designed for an easy fit, these systems include all necessary parts and hardware for a simple installation.
