Personally I don't see a free air 8" sub replacing the factory rear-deck woofer making that much of an improvement. I know others have gone this route but I've seen mixed reviews.
Personally, I'd suck it up and put a single 10" or 12" woofer in a small, sealed enclosure in the trunk. Feed it ~250watts or so and you'll have a good amount of bass and not alot of trunk room. There are MANY MANY subs that perform well in a small sealed enclosure, the Alpine Type R series being my favorite for a budget friendly install.
Personally, I'd suck it up and put a single 10" or 12" woofer in a small, sealed enclosure in the trunk. Feed it ~250watts or so and you'll have a good amount of bass and not alot of trunk room. There are MANY MANY subs that perform well in a small sealed enclosure, the Alpine Type R series being my favorite for a budget friendly install.
