Valvetronic Design Ford Mustang GT S550 Valved Sport Exhaust SystemWelcome to a revelation in the world of S550 exhaust sound. When doing headers, these cars can get extremely raspy and unruly. With the Valvetronic Designs valved exhaust system we have designed the perfect sound experience with a center resonator in order to lower rasp levels and deliver a clean and smooth sound for the driver and passers by. This system bolts up to the factory exhaust manifolds, but can also be adapted to fit aftermarket headers.