The pre-bent pipe sections used to join the headers and mufflers are 20 degree 1.75" ID/OD pieces, not even trimmed for length. They're not that easy to find in stock, but a couple auto parts stores were able to order them for me. They were fairly cheap, as I recall. Unfortunately, the inside of one of the bends is corrugated, while the other (which I prefer) is smooth. You'll see what I mean. Eventually I'll replace the corrugated one.
If I had any brains at all, I'd have written down the part number before tearing off the stickers, but oh well. It's been a while, but I believe I got them from NAPA.
I used Harley band clamps, which are unbelievably rugged, don't deform the pipes, and cost less than $8 each.
The hangers are 3/4" plated iron strapping cut to length and drilled. The lengths are slightly different side to side because the brackets on the mufflers are different. A key assembly tip is to slip everything together and get the heights and placement correct using whatever lengths of strapping are necessary, then slowly tighten the band clamps while keeping everything in alignment. Once it's all the way you want it, tighten the clamps very snugly. The clamps provide most of the rigidity in the system. I had to rotate the rear clamp on the left side so the bolt was at the top. Otherwise the centerstand hits the clamp.
The clamps the hangers hang from are the kind of thing that is used to attach a heater hose (for example) to a firewall. They are lined with rubber, which serves nicely in this case to keep the clamps from slipping on the frame, and it also keeps the clamp from marring the paint on the frame. I got them at Ace Hardware from the sort of drawers you get individual bolts from. They're nominally 1" in diameter, but they will wrap the slightly thicker frame tubing just fine. I used 1/4" bolts with Nylock nuts to keep the joints tight.
I cut a two pair of slots in the big end of the bends, lengthened the existing slot in the muffler and added a second pair of cuts at 90 degrees from them. This allows the clamps to shrink the diameter of the pipes without deforming them.
I had to dimple the inside of the left muffler about 1/4" in a couple places to keep it from rattling against the swingarm and the caliper bracket bolt when the muffler is placed at the same distance from the centerline of the bike as the right side, which has many fewer obstacles. The dimple is not deep enough to cause any deformation of the inner core of the muffler, and no such mod was required on the right side. They are essentially invisible on the bike.
Before:

After (So Far):

Closer:

Rear View:

Left side:

Closeup of simple hanger:

Richard