This muffler/ resonator is for use with BORLA mufflers 60637 or 60638 to add sound attenuation. Built from premium T-304 stainless steel, superior to T-400 series knockoffs (such as 409), to give you the absolute best in performance and durability. Ultra-smooth mandrel bends ensure maximum flow & power, and precision computer-controlled CNC manufacturing ensures an accurate fit. Best of all, BORLA stands behind every connection pipe with a Million-Mile Warranty. Just what you?d expect from the world?s most experienced (and most winning) exhaust brand.