Overall power output calculation>>>questions

[Thunderbruiser]

I was wondering how you guys estimate the overall power output of a setup

eg a mm7700 combo w/ maxamps 2s 8000mah pack vs. mm7700/6cell 3700(nimh) or vs the same size lipo with lesss mah

i am trying to better understand this as my lipo truck will be 10xl,18/52,4s8000mah what's the approx power output i'd be looking at?

also the mm7700 is in my buddies rustler lol