This 3" diameter into dual 2.25" BORLA Cat-Backâ„¢ system is tuned for performance and sound for both the 2.0L engine in the WRX and the 2.5L engine in the STI. Our S-Type sound level is designed to bring out the Subaru Boxer engine rumble and provides an aggressive sound without the drone. This system features quad (2 per muffler) 3.5" round high temperature black coated T-304 stainless steel tips but is also available with polished T-304 stainless steel tips. For ease of installation this Cat-Back is a direct bolt on part and does not require cutting. BORLA Cat-Backâ„¢ & Axle-Back exhaust systems feature patented straight-through and multi-core technology 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. Like all BORLA exhaust products each system is handmade in the USA by master craftspeople and features premium high-quality T-304 austenitic stainless steel construction precision computer numerical control (CNC) manufacturing ultra-smooth mandrel bent piping and a Million-Mile Warranty.