The Super 40® features Flowmaster's Delta Flow® technology. It's larger case profile provides the best of both worlds of performance and sound. The Super 40 has that deep powerful sound of the Original 40 series, but with a deeper tone, and all the benefits of extra performance and low interior resonance from the Delta Flow® technology. Constructed of 16 gauge 409S stainless steel and fully MIG welded for maximum durability.