Quick view Roush ROUSH 2005-2009 Ford Mustang GT/GT500 Enhanced Sound Dual Cat-Back Exhaust Kit - 403936 Compare $799.99 The Ford Mustang Exhaust Extreme Performance Kit gives your Mustang that rumble sound letting other's know you mean business while increasing the horsepower and torque of your vehicle. The increased power is generated due to the higher flow system as... Add to Cart Add to Cart