i have been wanting to put stacks on my truck, but if they are too big can my truck be messed up in anyway by having too little back pressure?

 

Uh I don't think so. Do a search on stacks, a number of recent threads on stacks. None mentioned damage from installing stacks.

Here is a picture of my meager (Some have 8" and a lot dual 7") 6" single. So far it has not messed up the truck, turned a few heads and makes it harder to control the occassional black cloud, but not other problems. LOL