I made a box for behind the seat of my truck its like a huge truck style box 59 wide 28 high 12 btm and 8 top, I calculated it was 7.7ft and went with 3x 4" aeroports. I ended up putting 4 12s in there then realized that every sub needed a port,I should have done 4x ports?? each port is 11" long i think im low 30s htz? my issue some songs sound decent and others like crap,and even with the decent songs the subs begin to smell a bit. Im running a Sundown 3500d each 12 is 1200w rms im wired 1 ohm. DO i need the 4th port??