Thinking about building a battery pack for my speaker system, need advice and/or guidance

[MrPleb]

Hey, so I'm thinking about installing a Sundown Salt-6 on my car and sorely need to upgrade my batteries before I do. I currently have a yellow top optima battery up front and 2 small 600w batteries(https://stingersolutions.com/products/600watt-secondary-battery) in the trunk trying to keep up with an Apocalypse AAB-4900.1D and it already isn't enough. Considering this will be a huge upgrade and from what I've seen the Sundown amp can do around 6900w at 1ohm before distortion, I NEED to upgrade before I put this amp in the car.

 

Now here is where I need help, I am by no means a professional and am seriously out of my depth but I'm passionate about my little projects and would rather ask for help than to let my ideas die. Now I've done some research and some back and forth with gpt and decided I'd take my chances here. My vague understanding of what I need from the battery and what gpt(AI) told me landed me at this set of cells(https://www.expertpower.us/products/3-2v-230ah-lifepo4-cells), they build a pack of 12.8v with a maximum of 14.6v, I have installed a high output alternator which charges my current batteries at 14.3v. The cells  have a maximum of 690a discharge current, which if what gpt(AI) said is correct should accommodate the maximum theoretical draw that the amp would need at peaks.

 

That is about where my understanding ends, and so I would love to hear what y'all have to say and maybe get some guidance or maybe I need to know some crucial information that I don't know yet. Thankfully I’m not entirely doing this alone, as I have people who are experienced with installing this kind of stuff who are willing to help me, I just need to know what path to start on.

 

I look forward to any replies!