In the process of undertaking the remote antenna mod, I discovered that the roof liner can be unhooked on the sides, and with a little effort, you can see inside to inspect the sunroof mechanism. Also visible is the metal strut (for lack of a better word) which stretches the liner accross the roof just behind the sunroof. I have had a rattle from this area since I got the car - and it has been the source of great annoyance. While poking around in there, I found that the strut, as luck would have it of course on the passenger side, had popped out of the clip (sleeve) which attaches it to the roof. A gentle push and a pop later, the strut is tight - the rattle is no more. Hope it lasts.

Stefan