Your battery bank depends on what your Alternators charging capability is. If you have a 200a alt, figure the car is going to require about 50-65a of that and leave the rest for the audio. So now you have 135a of charging capability from that alt and the rest has to be made up by the batteries. With the bc5500 and t-600, you are going to have the possibility of drawing 6-700a of current, not saying that is exactly what they are going to draw, but they could. I always plan for the worst case scenario when planning electrical systems.
The following is by no means the only way to calculate how many batteries you need, but has worked pretty well for me so far.
700a of current draw
- 135 amp of alt output
=565a battery support
D3100- 110ah
565/110=5.13
My recommendation is 5 XS Power D3100s in the rear along with whatever size XS battery is a direct drop in under the hood.
Hope this helps.