I currently have two 15's in two boxes with 5 cubic feet per sub. I want to now wall off my truck by adding two more 15's but the two additional boxes will only have 3 cubic feet per sub. I would like to run them all off the same amp. I know that to be optimum all subs should be in equal air space. But what will happen? Subs cancel out other subs? Sound like garbage? Damage subs? Damage amp? Or sound fine just not optimum setup? Just for reference, subs are DVC 4ohm, final load will be 2ohm, subs with 5 cubic ft will be on bottom with subs with 3 cubic ft on top, all boxes joined together into a wall. thanks in advance for any insight into this, I keep hearing different opinions on what will happen but no one I know has tried it.