If the battery you have now is good, why replace it? I would focus on a HO alternator first and use the battery you have. The reason I recommend this is a battery is a storage tank and the alternator is what makes the power. A QUALITY 200 amp alternator will produce all the power you need with ease and the battery will reinforce it. If you put a bigger or multible batterys only, your 80 amp alternator will be staining just to keep the battery charged, the power has to come from somewhere. I have a blazer with a 200 amp alt and a single battery, I can unhook the battery and run the Warn 9000# winch with no load and the voltage stays steady. NOW to the other extreme, my Honda has two XS Power batterys, and my 250 amp alt just broke forcing me to reinstall the factory alt. SO with ONLY the factory alt and TWO XS batterys, I have voltage drop even at moderate volumes. The math alone proves the point, but personal experience confirms the facts. You can buy a cigarette plug voltage meter at walmart if you don't want to install a permanent voltage meter.