The ROUSH Axle-Back Mustang Exhaust Kit with Round Tips, designed to fit the 2011-2014 Mustang GT & 2011-2012 Mustang GT500, is an innovative exhaust system from ROUSH that features an open-chambered designed muffler (as opposed to conventional fiberglass-packing). The result is an aggressive sound that is unique to ROUSH, increased longevity (with no fiberglass packing), and increased horsepower & with additional airflow. Another added benefit of this system is the lack of the in-cockpit boom normally found with performance exhaust systems at cruising speeds.