What type of upgrade do i need?

[Ronin]

Alright so i'm trying to put my system together right piece by piece and need some electrical suggestions. I will be running 1 15" AA Havoc,with either a SAE 1200D or AQ 1200D(leaning towards the AQ). My stock alt is 120amp,what type of upgrading do i need to get the most out of either amp? I have 0 gauge wire already,just deciding on new ho alt or upgrading front batt. or adding batt in back. If adding a battt in back which one and will it play nice with my staock alt and batt? I want my voltage to stay in the high 12's,wouldn't mind doing a 14v setup either,just don't know where to start,this will be my dail setup my start to dabble in some competing,thanks in advance.