I've said it before, but it bears saying again: it's a good thing I don't do this for a living. I've been dicking about with the angle of the muffler and the connecting pipe now for days, without finding that elusive, perfect solution.
I tried the shallower, scrambler-looking position (see last post) for the muffler for a couple of days, but I just COULD NOT get the link pipe between the 2-into-1-pipe and the muffler to look good. The angle and curvature of the link pipe clashed terribly with the angles of the frame. It looked like an afterthought (which in essence it was - but don't tell anyone...). I now have a whole heap of discarded pipes on my work shop floor, and a new-found respect for people who make exhausts as a regular job.
As you can see, I have now gone with a much steeper angle for the muffler, which makes the link pipe much easier to get right. It's now parallel with the support strut for the seat and doesn't break with the overall lines of the bike. The increased angle (which was suggested by "Outacontrolla" BTW) actually looks more flat track than Scrambler as well. Or is this just my brain trying to justify my decision to give up on the other position? Hm. Next up: moving the mounting point for the muffler a little bit backwards and fabricating a little hanger to replace the strip of duct tape. I don't fancy the "clamp hanger" that came with the muffler.