Fitment Information Honda Civic Si (2017, 2018, 2019, 2020, 2021) Select coupe or sedan in the options 1.5T Specs & Features Piping: 3" Tip: 4" T304 Stainless Bolt On Emissions Compliance This is a catback exhaust and does not alter, replace, or modify any emissions equipment Product Description Dynamic, Tuned, SystemDT-S Exhaust systems feature a clean design with an emphasis on creating a dynamic and deep exhaust note. These exhausts are made to have an aggressive volume with uncompromised performance. Perfect for street and daily driving, quiet at lower RPMs and aggressive at high RPMs, experience the DT-S Exhaust. Advanced Metallurgy The best materials were hand picked for ideal performance and enhanced strength. Science of Sound The harmony of the signature ARK Performance mufflers with Helmholtz technology provides all the best sounds while leaving out the drone. Designed to Flow Beautifully crafted mandrel bends and x-pipe provide a true and even flow that is hard to match anywhere else. The Finishing Touch Each exhaust system comes with tip finishes and options that provide that perfect accent to any vehicle.