deep cycle bats are not the best thing for systems, tho a bunch of people use them. deep cycle bats arent designed to slew all their current out at one time, more over a period of time, so they stay charged longer for stuff like trolling motors.
to handle transient peaks in current, for things like music with the car off, or burps in competition, you want a quick charge/discharge bat like the red top or reg car bat that is designed to give you everything it has all at one time, and recharge quickly enough to handle the next attack.