You're not reprogramming your ESC. The endpoints on the tactic radio are just digital rather than a dial like on most RTR radios. End points are the maximum output instructions delivered from the radio to the car. If the throttle endpoint is below 100% you won't get the most speed out of your car. End points are like a rock under your gas pedal. If your end points are set too far from maximum, you have a big rock under the gas pedal. If they are closer to maximum, you have a smaller rock under the gas pedal. If they are set to maximum you have NO rock under the gas pedal and can go full throttle.
End points are useful for new drivers or if you constantly destroy tires or can't control your car because it's just too fast. Also, if your car tries to roll away on its own without throttle input, you need to adjust your endpoint back a notch or two.