When I got my Boxster, there was a rattle in the passenger door when I went over bumps. I recently replaced the window regulator in the driver's door, and I gained the same rattle there. This weekend I opened up both door panels to figure out what was going on. I saw the regulator had also been replaced in the passenger door previous to my ownership, so I started to suspect the rattles had to do with the regulator. I starting moving and jiggling stuff, and I could replicate the rattle sound by moving the window regulator cables around. I added one zip tie to each door to secure the window regulator cables. Not too tight, just enough to keep them from moving too much. Rattles gone!!!!!