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 wrench!These 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 offset/offset Mufflers that are designed to fit many car and truck applications including most Ford Mustang applications.