This system includes the adapters needed to match the different pipe diameters coming out of the catalytic converters. Some pipe from the outlet end of the catalytic converter will be needed to mate up with the adapter. This Cat-Back™ system is unique in the industry with an adjustable sound level. By changing the block off plates behind the center tip you can adjust the SPL (Sound Pressure Level) to your taste. System features dual 2.5" round polished T-304 stainless steel tips on each tail pipe. BORLA Cat-Back™ & Axle-Back exhaust systems feature patented straight-through and multi-core technology designed to unleash hidden horsepower. Increased exhaust velocity adds power, driving excitement, fuel economy, and the distinctive BORLA Sound of Power respected by motoring enthusiasts everywhere. Each system is 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 numerical control (CNC) manufacturing ensures an accurate fit. Best of all, BORLA stands behind every system with a Million-Mile Warranty. Just what you'd expect from the world's most experienced (and most winning) exhaust brand.