3" diameter system. Adding this resonator to the 11933 Axle-Back system and the 60622 Mid-Pipe assembly will achieve the "Touring" sound level or it can be used with the 11934 ATAK(r) axle-back system and the 60622 Mid-Pipe to make a quieter version of the ATAK(r) system. Use ONLY with Borla(r) systems. It is NOT designed to be used with competitor or Original Equipment systems. 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 fit resonator with a Million-Mile Warranty. Just what you'd expect from the world's most experienced (and most winning) exhaust brand.