Advice for dual batteries/charging upgrades

[SICKSPD]

Alright so I realize that eventually it will come time for me to upgrade my alt and power runs, BUT as of right now Im thinking about just adding another battery. Right now I have an XS D3400 and I feel that my system needs some more backup charge. My challenger is PCM controlled and I know how these cars are about voltage fluctuations so I want to make it as stable as possible. Now what I want to know is…would it work fine if I use a smaller sized xs power like the d925 wired in parallel to the d3400? Both will be in my trunk.(factory location for the battery is in the trunk) My system will see around 2200 watts RMS at most once I'm done with the audio equipment. The factory alt i believe is rated at either 160 or 170 amps.

I haven't done the big 3 yet, I will do the 1/0 grounds soon but the power wire run will be a very difficult task as dodge poorly designed the space for wires around the firewall. The stock power run appears to be 1/0 but theres about a foot long bottleneck where it goes to 8 ga. then back to 1/0 (dumbest thing ever).

So anyways what are yalls thoughts on running a same brand agm battery but with different specs and keeping the stock alt for the time being? Will my system be a lot more stable? I think that about covers what I was wondering.