The RPT slip-ons make use of all of the high-tech features of Cobra's regular 3'' slip-on mufflers, including 2'' constant velocity cores for exceptional sound and performance, as well as the bonded e-glass and stainless steel meshThe RPT designation comes from adapting the design from Cobra's Race-Pro 4'' muffler into this three-inch sizeThe bodies begin as 3'' at the front until they expand to 3.5'' inches at the rearThe tip uses the Race-Pro machined design that's held in place with 12-point bolts