On a related subject, I found that the PO or PPO, more likely, had removed
the door vapor barriers to rehab the power windows on my van. I did an audio
upgrade a few months ago (Alpine 5 1/4's with directional tweets, sound
great but the grills touch the dash) but I didn't even realize that there
should have been a vapor barrier. Now I know that I want one, since the
winter moisture combined with my dash-touching speaker installation has
caused a bit of door panel warping.

So... what should I use as a vapor barrier? Any online sources for that?

Thanks,
Peter