Car audio install with dual battery set up help!!

[Rickstar2023]

Hey I’m currently doing a car audio install in a 2018 Kia cerato YD and I need some recommendations on that to do I’ve done some installations before but none with a dual battery set up I’m planning on using a 200-250a alternator and a slimline 170AH AGM in the back I’ve heard some people say just use a isolator whilst someone from a car audio shop says to use a regulator or Dc-dc charger I’ve looked everywhere for a reg or dc-dc that is 200-250a to keep up with the power draw from the 2-3kw monoblock I’m planning on getting i already own the battery and the sub but no idea what to do after the advice that if I don’t use a dc-dc or reg my battery might get too much charge and go short circuit and act like a welder so no idea now what to do 

 

idk if I’m allowed to post links I’m new here

link to the alternator: 

https://www.powerbastards.com/proddetail.asp?prod=14962-250-HD1-1

 

theres also a stinger alternator that’s a 220a but I don’t have a link it would be custom made 

 

Cheers Rick