Yes, at least the 38 mm (1 1/2") OD pipes that I have on my XS only attach to the head. And to the mufflers obviously. I got them from Jerry Heiden in Holland, but Heiden and MikesXS have the same pipes.
So if you want to run "straight" pipes and no muffler they are not the best choice. But straight pipes are crap for performance anyway, so that isn't a real problem. The "Commando" or "XS1" mufflers from MikesXS or Heiden have a decent reputation and are fairly low price.