These new BBK Varitune axle back exhaust systems feature BBK Varitune mufflers that have a patented adjustable power valve inside that allows full adjustment of the exhaust flow through the mufflers chambers for a great sound and added performance. This adjustment is made at the rear of the muffler with a wrench by either moving the valve in or out. Once you are happy with the level of sound it is locked in place with the Varitune locking nut. All of the Varitune power valves are made with stainless steel for lasting durability and smooth operation. These patented BBK Varitune exhaust systems allow you to personalize the power and sound levels of your car 8-10 decibels and 10-15 horsepower. All kits are available in 439 stainless steel and are offered as direct bolt on replacements for the restrictive factory exhaust. Every Varitune exhaust kit includes BBK Varitune laser etched logo 4" brushed stainless steel tips for impressive looks.