WRX STI PERFORMANCE TURBO MUFFLER CATBACK EXHAUST SYSTEM SET JDM BLACK Fitment: 2002-2005 Subaru Impreza WRX / STI Catback Exhaust System SUS-304 Stainless Steel Made with Black Finish on Canister. Comes with a 4.5" Tip Designed for high performance as well as meeting sound level standards. With its deep throaty tone, it echoes its racing lineage. Optimize torque in the low to mid speed range 3" (~75mm) N1 Design to Gain More Horse Power, Faster Response, Averaging 10-15 Extra HP PROFESSIONAL INSTALLATION IS HIGHLY RECOMMENDED. NO INSTALLATION GUIDE IS AVAILABLE.