here's how to plug off the r/s pipe on the rear cylinder. take a 1 5/8 in. core plug ($1.68) and sand off a bit on 2 sides. the plug will just slide into the exhaust pipe past the crossover joint. rotate the plug so that the crown faces the rear cylinder. with a 1/4 in. hole drilled thru the pipe on both sides, the sides of the plug should be visible in the holes. tig weld or mig weld the pipe to the core plug. you will have to measure where the holes should be in the pipe so they will hit the side of the plug when seated close to the crossover joint. tack a welding wire to the crown and use it to help align and seat the plug. replace pipes and heat shields. factory true duals.