- Catback exhaust systems are made of Stainless Steel with a fully polished surface, CNC machined flanges and mandrel bends. Its aggressive styling, and deep, strong tone are just part of the MR exhaust system characteristics. It also serves to improve horsepower, torque and overall performance with its straight-through design. Finished with a tip that is designed to increase the scavenging effect and achieve maximum performance, while adding a perfect match on exterior styling as well. It's really easy and convenient to use: direct bolt-on, no modification needed.