too much heat often comes from a under rated li-po, and you can fix it without buying a new battery, and if you keep doing what you've been doing with it, then you probably won't need a better battery. The new wheels and tires are going to help a ton, they're the same kind i have, but you'll also want a better spur gear.
48T 50T
with a monster like the muggy I think that you should consider at least a 6S pack for your next battery, but not a maxamps, lincpimp said he's had 12 different maxamps batteries and he's had to send them all back, he recommended for me to go with anything that uses enerland cells, I think you should too, he said that any flightpower, neuenergy, thunderpower, polyquest, or poly rc pack will be exceptional, they use enerland cells. This is the one i'm getting:
http://www.amainhobbies.com/product_...ducts_id/17987
Edit: and that is a truly awesome avatar