I’m running 9000w rms right now in my car with no capacitor or upgrades, it’s all stock, running off just the battery. You won’t really need any upgrades, but buying a capacitor will help with starving subwoofers. But your electrical system should be fine, 220a is good enough to run that electrical system for 2500w. So I recommend buying a capacitor, like a 2-fared capacitor.
edit 2024: Don't buy a cap, they're stupid. Buy a second battery, preferably a lithium. And get a high output alternator, stock sucks, definitely can't do 9000 rms, the amount of times I had to jump my pos is crazy. Past me is a fuckin retard.