Touring Series™ Stainless Steel Cat-Back Exhaust System with Dual Rear Exit by MagnaFlow®. Exhaust System Type: Cat-Back. Exhaust Tubing Material: Stainless Steel. Main Tubing Diameter: 2.25". The Touring Series exhaust systems are tuned for everyday driving, with a deep and mellow exhaust note of true performance character but at a decibel level and tone that does not get tiring even over long hauls.