2nd or 3rd Battery help?

[1BAD4DR]

I've been having problems with getting strong sound from my speakers. If i would turn it up past halfway the sound would get all muddy and actually get quieter. So i replaced the big 3 and got the kinks out of my door and deck speakers. The problem is my sub is still hitting pitifully. I have a couple small deep cycle's laying around but i think my biggest problem is voltage not amperage.

Heres what i got.
US Acoustics D1000(I have had this pushing 3 jl w7's in other cars 1ohm with 3/4 gain)
US Acoustics 4 channel 125 x 4 running doors and deck

polk components up front and polk 6x9s in the rear

trying to push a mtx 9500 15...Its 2 ohm because at some point i plan to run 2 and want that to run at 1ohm.

Has anyone heard an improvement by adding batteries to this type of scenario?

[CrEaTrE]

You should not need a second battery with that setup. Something is wrong with the wiring or the tuning. Refer to the tuning and subwoofer wiring sticky's to make sure you have everything tuned correctly, and that you have everything wired like you want.