Fixed my door rattle, (it was the subwoofer/speaker thing)
 

Wound up being the speaker, the subwoofer thing. 2 of 3 screws were totally out, being held in place by the liner.

Anyone have the same experience?

Wait, so before when you closed the door would you hear a rattle sound? I'm having a similar problem on my passenger side door, but it's only when the window is down. Obviously it's the glass but the service guy at the dealer had no clue.

I had 3 very loose screws on mine. Some guy on the assembly line must have had an sore hand for a few weeks.

It rattled up or down. Your window might be loose, that was the first thing I was checking for. There are 2 easy ones you can check. Under your doors, there are 4 black oval covers, remove the 2 inside ones, there you will see some nuts, tighten those. If that is not it, search the forum, and look for 2 spots on the door to tighten the window when it's in the down position. I JUST deleted the links I used, and can't find them. I still have this link, it shows how to take apart the door panel, really simple, less than 4 minutes to take it apart.
http://images2.wikia.nocookie.net/boxster/images/b/b6/Boxster_speakers_update_article.pdf

Don't tighten too much, you will shatter your glass.

If that's not it, check your door speaker, like we said, the screws were totally out.
it's the black thing inside the door, once you peel back the protector sheet.

lmk if you have any questions I'll try to help.

It's common to have door latch rattles on these cars. Try wraping a piece of electrical tape around the U-shaped chrome strike where your door latches up. Wrap (2 turns) the piece that is perpendicular to where it mounts (you'll see a minor amount of wear on that leg of the U-shape). Some people replace them or attempt to adjust them, or flip them to provide a fresh wear surface. I change the tape wrap around once per year and my door rattle is gone. I had taken the door apart and found the loose speaker enclosure, but that only rattled when music was bassey.

Let us know the outcome, whatever you find.

Bob

Door window rattle
 

In my case, my 2002 Boxster had had a replacement window regulator installed at some point before I purchased the car. There are two spots for the lower window stop: low and high. My car had the stop in the low position - the window would travel too far into the door and the top edge of the window would not seat against the rubber lip. I moved the stop up. No more rattles.