right now I have 6sa12s 2 saz-3000d. Thinking about walling my truck off so that I can fit batteries, get my box to the right size, and get louder period. I have been wanting to go to 4 18s. Can't really afford to get sundown 18s right now. Do you think I should stick with what I have or I have been looking at the SKAR ZVX-18s. All of this has to fit behind my third row