Okay so I am thinking about upgrading my subwoofers but i need major help because have to change everything?

anything over 1200 watts RMS you need 2 to 0 awg wire for power and ground cable, also if you have something like 1200 RMS per subwoofer you need some thing at least 12 awg speaker wire. I really like the RE audio XXX series, 15 inch is what I would recommended. you need upgrade the battery for sure, get at least 2 more in the trunk also use the 2 of the Massive auido N4 amplifier at 1 ohm load dude you'll be loud as hell.