I have a 91 hatchback too and i run a dd9512G and it gets crazy loud. Im changing my set up because i dont want to run 3 batteries in the trunk with that big amp and a big box with that 50 lb sub. Im going for more speed now and less weight is always better. You need to figure out what your price range is but if youre gonna do 2 of any of those subs above I would consider the kicker but if youre gonna upgrade think about how much space you want to give up and your budget. Remember the hatchback is not high all around. The height drops as you move towards the rear. I would consider some of the other subs mentioned above from these guys. Your fox will get loud easily because its a hatch.