Good points, by using a litium battery big enough to supply current for a low mod motor you would need the bigger 8000mAh pack. I ran with the Novak 5800 with a 4000mAh pack and worked great, but as the battery location was the side of the car, the balance was off. So your car might need a central or slit pack to balance properly.
Most average Lith at this time can dump 10C so for the 8000mAh pack you could get 80 amps from it.
Some new liths can dump as high as 20C, now there you could use the 4000 pack, lose about 6oz and probably run for 10 minutes, make it an 8 minute race so there is no battery war.