alternator upgrade on 99 cherokee

I bought a mean green alternator it says to output 300% more but they don't tell you the amps. I plan on replacing and i m also putting in a die hard platinum battery which has the concepts of a optima battery. They say to just pop it in and not replace any wiring but i don't believe thats what i should do. I want to run a good 4g wire to the alt. heres a picture below that shows my diagram sorry it looks like a grade schooler made it haha. It seems the power goes to the fusebox then to the alternator also 2 small gauge wires goto the plug on the alternator which are small grounds I'm guessing they 0 out on my dmm. Theres no power going from battery straight to the alternator. Any advice on wiring up this mess?