this is my ride right now, my money maker(yes this is a semi), looking for sub and amp to get me some bump.they make a pretty decent stock system in these. 6 speakers total with factory freightliner model cd player. im basically looking to get some kind of bump and keep it small. theres not much room anywhere except if i drop the top bunk. the bunk space up top is about 6 feet in lenght and about 3 feet wide so making proper enclosure size wont be a problem, but at the same time i really dont want to drop more then about 400 bucks on this and it needs to be easily removed...any ideas??