The TC Bro just came out with a DIY exhaust kit specifically for the XS650. I got mine in the mail yesterday. The Kit has a grip of pieces including 2 flanges and collars to fit your stock XS650 head, 2 mandrel bent 90 degree pieces, 2 mandrel bent 180 degree pieces and 2 straight length pieces.
Tubing is 1.5 inch diameter 16 gauge steel; so now you don’t have to use the crappy car exhaust tubing you got from the auto store. There is enough tubing supplied to play around and make whatever crazy exhaust you can come up with.