Under the carpeting in my 99 G20 I noticed 2 rubber caps on either side of the trunk, with the words (if i remember correctly) 'PVC' on them. Any idea what these are? Thanks!

do you mean the tubes which drain out water ? theres one right next to your antenna and one on the other side

Thats what I thought originaly they were, but there placement doesnt make sense, i know there is a big one underneath the spare that is for draining water. But these 4 don't open directly to the outside of the car, there are some sort of metalic trough/beam thing.