If your want the most aggressive sound in the Flowmaster line of mufflers you came to the right place. The Flowmaster 40 Series Mufflers are designed for use on both street and strip vehicles. Angled baffles built into the muffler case are used to cancel sound waves produced in the exhaust. Doing so heightens both fuel economy and horsepower. The Flowmaster 40 Series Muffler produces that original Flowmaster sound both outside and inside your car.