ORIGINAL: burnineyes
The 25A ESC will be plenty, they generally under-rate them so that they will seem more reliable.
As for the gearing, if the motor runs cool and you like where you are with acceleration and top speed then no need to do anything. Generally for each tooth you drop on the pinion you will lose 1-2MPH, but in some cases the added acceleration makes the car feel faster. If you are overloading the motor you can pick up top speed by dropping pinion size, but it will run hot if you overload it. Your choice in gearing is all dependent on how you want the truck to drive, your only limiting factor should be heat.
Awesome, thank you very much! I only ran the truck for maybe 5 minutes but I was doing nothing but speed runs and hard acceleration, so I figured if it was going to heat up it would have. I just ordered some Zippy 3s 1000mah batteries from hobbyking so we'll see how it screams with some "real" batteries!