I have a 93 xlt with the jbl premium sound system..im on a tight budget so i was thinking about replacing the existing sub in the back..does anybody know how big it is or how big of a sub i could fit in there..i was hoping to put in a 12 but i don't know if it will fit..do u guys think this is a good idea though? would i get better bass than im getting right now with the stock? i also want to get a better amp to power the sub..what brand names do u guys suggest for the sub and amp? remember im on a tight budget..any suggestions r appreciated..thanx