Dynomax 54799 Ultra Flo Welded Muffler Assembly Stainless steel construction for lifelong protection Straight through design ensures unrestricted exhaust flow and reduces back pressure CRF Technology absorbs unwanted interior resonance while maintaining a deep performance tone 100% welded design for maximum durability Dyno proven to flow up to 2,000 SCFM and support up to 2,000 horsepower.