Use the sand bending method.
http://www.rorty-design.com/content/sand_bending.htm
They have them on Ebay but they probably wouldn't be as nice as you could make them. I wouldn't mind trying a couple bends on my friends machine but I don't have any thinwall tubing on hand. You'll have to flare the ends a bit as well. Of course I'm thinking about making some on the verge of overkill though. I've seen some really trick racing exhausts that people have made for their vintage Honda racers.