Split Rear™ Aluminized Steel Cat-Back Exhaust System with Split Rear Exit (5532) by Gibson®. Exhaust System Type: Cat-Back. Exhaust Tubing Material: Aluminized Steel. Main Tubing Diameter: 1.75". Exhaust System Sound: Aggressive / Loud. Get increased horsepower and torque in the rpm range where you need it most, along with the look of dual exhaust, with the Split Rear Cat-Back Exhaust System. This Gibson exhaust system makes maximum low end power, which is best for towing, general performance and increased fuel economy, with an aggressive, throaty exhaust tone. It's made of aluminized steel and comes with dual exhaust pipes and dual polished stainless steel exhaust tips that exit straight out the back.