i think i got some of the same baffles. Well i can tell you i get better mids and lows from the speakers now that everything isnt lost to the trunk. I would assume that you would get at least some protection from subwoofer vibrations, but the ones i got seal well so they should be inpenitrable for dirt/water/dust. You will have to do some mods to the speaker carriers because real 6x9'* are a bit larger than the stock ones... (at least mine were) but that is easily solved with a sharp razor or tin snips. and when your installing the baffles youll be glad that they are flexible because they have to mold a little to the carriers and the car.
I just got the 6x9'* because i wasnt sure if the 5-6'* were too deep for our doors...
'94 Bonneville SE - 106k miles 6/1/07