Would it be crazy loud if I just ran straight pipes out the back from the headers?

Cheap glass packs have always sounded good to me, or you could even make your own baffles and "tune" them the way you like, that's what I did on my wife's 300. I welded up some baffles and bought fiberglass packing material off of eBay, sounds great and performs well.
Well, I most definitely want to save money as I have spend WAAAAY to much money on the drive train, wiring, and pretty much everything since I started with a stripped shell of a Dart...