Flowmaster 5403112 30 Series Delta Force 4.00" Offset In and Centre Out 16-Gauge Aluminized Steel Race Muffler Durable fully welded 16 gauge aluminized steel - two chamber race muffler Good decibel reduction over open headers No internal packing to blow-out Race proven patented delta flow technology - designed for maximum horsepower and torque Contains three chambers and reduces the exterior sound level as well as interior resonance