Flowmaster's stainless steel 50 Series HD muffler is designed for today's heavy duty gas and diesel trucks. This muffler delivers improved performance, throttle response and mileage. The 50 HD features a deep, moderate tone with minimal interior resonance and is ideal for trucks with modified engines. This muffler is constructed of 409S Stainless Steel with a 3.5" inlet and outlet, and is covered by Flowmaster's Lifetime Limited Warranty.