Flowmaster American Thunder Cat-back Exhaust SystemFor the person who wants the look of a traditional dual exhaust system with all the benefits that a Flowmaster Cat back exhaust system provides. This dual out American Thunder cat back exhaust system is the perfect choice with a 2. 50 inch flanged pipe connecting directly to the catalytic converter and quickly transitioning to a full 3. 00 inch mandrel bent aluminized steel inlet tube flowing into a large case 80 Series Cross flow performance muffler