This Resonator is designed to replace the Merge X-Pipe in select BORLAÂ 140590 and 140591 Cat-Back systems to dampen the sound. It is NOT designed to work with competitors or Original Equipment (O.E.) systems. The resonator contains an internal H-Pipe for increased performance and improved sound. Dual 2.25" diameter inlets dual 2.5" outlet. Resonator features an internal H-Pipe for increased performance and improved sound. 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. Precision computer numerical control (CNC) manufacturing ensures an accurate fit. Best of all BORLAÂ stands behind every Resonator with a Million-Mile Warranty. Just what you'd expect from the world's most experienced (and most winning) exhaust brand.