BBK Performance Parts Vari-Tune Performance Mufflers are the first of their kind, a fully adjustable performance muffler. These mufflers can be adjusted for sound and horsepower by simply moving the adjustment screw in or out from underneath the car. The patent-pending adjustable chamber valve assembly permits sound level adjustment of 8-10 decibels while simultaneously changing the power level. Available in aluminized or stainless steel and offset design features 2.5", 2.75", or 3" outlets.