2003-2009 Nissan 350Z INFINITI G35 Coupe Dual 4.5" Tip Muffler Catback Exhaust SystemDescription Upgrading vehicle's exhaust system is a great way to build horsepower, free up trapped torque, and improve upon restrictive factory systems. The larger pipes, low restriction mufflers, and tuned resonators of a well designed performance exhaust system can make a world of difference in your vehicle. The net result is lower auto exhaust backpressure, more horsepower, more torque, and a much better sound. Features Inlet Outlet Diameter: 2.