update: i went ahead and purchased the polk audio db691 6x9 speakers from circuit city.
me and a co-worker got them installed in about 20-30 minutes, due to a lack of proper tools. they initially did not line up with the factory speaker holes, but after moving the speaker around, we were able to get all the screws to line up and bolt down. the factory speaker grilles in the rear fit perfectly snug and secure over these speakers. no real fitment issues whatsoever.
as for the speakers themselves, they perform pretty well with the factory head unit. the sound is very even now compared to the factory speaker and there is actually bass in the backseat now as a result of the upgrade. the highs are more crisp and clean sounding with these speakers. they are an excellent choice to upgrade the rear decks if you are looking for better and more even sound quality from the rear deck.
