These patented BBK Performance Varitune mufflers are the first of their kind in the aftermarket, fully adjustable performance Mufflers that can be adjusted for a louder or quieter sound and horsepower by simply moving the adjustment screw in or out from underneath the car with a wrenchThese mufflers are available in 439 stainless steel, in 2.5 in., 2.75 in. and 3.0 in. and with various offsets to fit most aftermarket and OEM applications.These are offsetoffset Mufflers that are designed to fit many car and truck applications including most Ford Mustang applications.