Greg I also used the kit muffler for my expansion pipes. Did you notice much change in performance by adding the muffler? I used the long style rather than the crossover banana pipe and cut the stinger off to keep the overall length of the pipe with muffler the same; whereas you increased length, I'm guessing that is a plus in keeping oil off pant leg. My pipe, long high pipe, extends to the rear axle with muffler in place.
Give us a performance review om your setup. I really like the finished look with the muffler installed.
Rick C.