Rev9(CB-012) Volkswagen MK6 Golf GTI 09-12 2.0T TFSI Turbo Stainless Cat-Back Exhaust Tip size is 3.5" with 2.5" exhaust piping CNC machined flanges for strong solid support TIG welds for strength and durability Increase 20-25 horsepower and torque No Install Instructions, Install Perform By Experienced Professional Installer Is Recommended. For Off-road and Competition Use Only Due To Federal Emission Regulations.