Street Series™ Stainless Steel Cat-Back Exhaust System with Split Rear Exit by MagnaFlow®. Exhaust System Type: Cat-Back. Exhaust Tubing Material: Stainless Steel. Main Tubing Diameter: 3". MagnaFlow Street Series Performance Exhaust systems deliver the smooth deep sound you want and the wide-open performance power you need. Exhaust systems feature straight-through flow designs for the ultimate in unrestricted horsepower and torque for big power while maintaining exhaust efficiency. These systems are an engineered balance of interior and exterior noise levels and are tested against SAE j1169 standards.