I have the NTC3 RTR - it only comes with a single speed so I installed the 2 speed upgrade. Tech support claims with 2 spd upgrade it gets low to mid 50's. W/ single spd it gets low to mid 30's. I am playing with my gearing on mine. I order new pinion and spur gears for it and should be in next week. This is what I am doing.

For Nitro TC3 RTR from team associates the transmission ratio is 2.5 This is not in documentation. I called and asked tech support.

You want a higher # for final drive ratio for first gear to get more acceloration and more torque. You want a lower # for final drive ratio for second gear for more top end speed.

In general, installing a smaller pinion gear will give you better
acceleration while installing a larger pinion gear will improve your top
speed. The opposite can be said to be true when changing your spur gear. A
smaller spur gear will give you better top speed while a larger spur will
increase your acceleration. When making changes to your model's set-up, it
is best to make one change at a time, testing after each change and
recording your findings.

Stock 2 speed gears:
Spur divided by pinion = gear ratio X transmission ratio = final drive ratio
1st gear
50/22=2.27x2.5=5.68
2nd gear
54/26=2.07x2.5=5.19

Upgraded gearing (pinions only):
1st gear
50/20=2.5x2.5=6.25
2nd gear
54/27=2x2.5=5

Upgraded gearing (pinions & spurs):
1st gear
50/20=2.5x2.5=6.25
2nd gear
48/27=1.77x2.5=4.44

Attached is a pic of my NTC3 - This is not my racing body, just my pimping around my neighborhood body.