Did a 2:1 with the stock exhaust header,just got back from a good ride and the lost torque from the slip- ons is back,feels real smooth now through the throttle power wise and still has a good bark.pretty happy with it.took off left crossover pipe,put in a 40mm freeze plug to the right side pipe and reinstalled left side.can be removed if need be with no problems,and only cost a couple bucks at the local napa.