It sounded decent even though the Audiobahn subs I used weren't ideal for free-air use. A
Dayton 8" Quatro would be a good choice if I were to do it over. Rear deck subs good choice if you want to fill out the low end of your system and don't want to give up any trunk space.
I've since replaced them with a single 12" Lambda PB due to more bass cravings.