A performance exhaust system is a superior replacement for a manufacturer installed exhaust. These systems increase torque by speeding up the exit flow of waste gases from the engine and cylinders; this consequently improves gas mileage.
Some improvements these systems have over manufacturer installed exhausts include pipe shapes and diameters that improve air flow and higher quality materials such as aluminized steel and 304 stainless steel. Some exhaust systems also include mufflers that change the sound the exhaust pipe makes when in use.
MagnaFlow and Flowmaster provide professionally made performance exhaust systems, including the MagnaFlow Off-Road Pro Series straight-through system for gas and diesel trucks and the Flowmaster Force II system with mufflers for sedan models.