These resonators are used to convert a 140633 ATAK(r) system into a S-Type system. Use ONLY with Borla(r) systems. It does NOT fit with competitor or Original Equipment systems. 2.75" diameter system. Built from premium T-304 stainless steel, superior to T-400 series (such as 409), to give you the absolute best in performance and durability. Ultra-smooth mandrel bends ensure maximum flow & power, and precision computer numerical control (CNC) manufacturing ensures an accurate fit. Best of all, Borla(r) stands behind every direct ift resonator with a Million-Mile Warranty. Just what you'd expect from the world's most experienced (and most winning) exhaust brand.