aFe's Takeda stainless steel cat - back exhaust system brings the power and sound to the 2017 - 2018 Honda Civic Si Sedan with I4 - 1.5L (t) engine. Constructed from 3 to 2 - 12 mandrel bent, 304 stainless steel tubing improves exhaust flow to deliver up to 10 HP and 11 lbs. x ft. torque. 100 hand TIG - welded by certified craftsmen for race proven strength and durability, the Takeda system incorporates dual, free - flowing 304 stainless steel mufflers to improve performance across the power band while maintaining an aggressive tone and long lasting, good looks. Finished with dual 4 - 34 X 4 - 14 oval black tips etched with Takeda brand logos gives the Civic Si a track - style, custom appearance. Performance Gains In testing, the cat - back exhaust system resulted in gains up to 10 horsepower and 11 lbs. x ft. of torque, as measured on our in - house dyno. Aggressive Sound Dual, free - flowing, 304 stainless steel mufflers are used to absorb high pitch tones producing a powerful sound and unleashing more horsepower and torque potential. Dual Round, Double - Wall, Angle - Cut Black Exhaust Tips This dual rear - exit system features round, double - wall angle - cut, black stainless steel exhaust tips w laser - etched Takeda logo for a custom appearance. Installation is a snap This Takeda exhaust system uses all factory mounting locations providing stability and a hassle - free installation. Perfect Fit OE - style bayonet hangers are used to maintain a stable pipe location during any driving conditions. The bayonet tip holds the hanger bushing in place for an OE style, long lasting fit. Leak - Free Seal High quality band clamps are used for a complete 360 - degree sealing surface.