Gibsons exhaust systems decrease back pressure, allowing the engine to produce more torque, increase horsepower. Typical gains average of 15-20 horsepower. On some vehicles the spare tire may need to be relocated or removed. Works with most bumpers, roll pan and trailer hitches. Not recommended for towing, because carbon monoxide may be drawn into the interior rear of a vehicle when an exhaust pipe directly exits to the rear of the vehicle. Exhaust can be louder under towing conditions.