I drive a small car with a 70amp alt and a regular battery up front and with a kicker zx750 and a old sony 50x4 my lights dimmed.

I currently am running like 100x2 for my subs so its not dimming but I am looking at 1200-1500rms for bl 15 most likely. I am wondering if putting a kinetik in the trunk is enough or if my alt won't even be able to keep up.

if your just running that sae 1200 and even a 4 channel,you should be fine just do the big 3, and hook up the second bat!!