The K-Tuned 8th Gen Civic Cat Back Exhaust System uses a proven design to reduce restriction and deliver significant power gains, especially in the upper rpm range, where the K engine loves to breathe. For piping, we used large diameter 3" mandrel-For a good balance of price and performance, Invidia offers the motorsport enthusiasts a strong line-up of Invidia N1 Exhausts. Each Invidia Exhaust is constructed with high quality SUS304 Stainless Steel, CNC-machined flanges, and manufactured with a polished finish. Each system features mandrel-bent stainless steel piping for maximum exhaust flow and reduced back pressure. These exhausts are engineered to produce strong mid to top-end power gains, as well as an increase in horsepower and torque.