Borla Cat-Back and Rear Section 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 enthusiasts everywhere. Each system is built from premium 300 series austenitic stainless steel; superior to T-400 series knockoffs; to give you the absolute best in performance and durability. Ultra smooth mandrel bends ensure maximum flow and power; and precision computer controlled CNC manufacturing ensures an accurate fit. Best of all Borla stands behind every system with a Million-Mile Warranty. Just what you would expect from the worlds most experienced and most winning exhaust brad. S3 15-18 2.0T AT/MT AWD 4DR D RD RL AC SR 3.0in.; 2.25in. S-TYPE TIPS 3.5in. RD X 6in. Million Mile Warranty 2015-2018 Audi 8V S3 2.0L 4 Cyl. Turbo All Wheel Drive (AWD) 4-Door.