The NTC3 is better for racing.

The NTC3 RTR is only s single speed. It only goes between 30 - 35MPh - add the 2 spd tranny then you can get 50-55MPh.

Take same 2 spd and put the TRX 2.5 motor. I bet it would rip. But since the NTC3 come with a .12 and the TRX 2.5 is a .15 motor - I would expect some performance difference. You can get more power out of NTC3 with the Mugen .12 MT2 and regear the tranny.

I have heard a lot of people at the track complain about the handling of the TRX Nitro 4-Tec

I have the NTC3 RTR w/ 2 spd upgrade, then I regeared the 2 spd to the following:

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

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

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

3 - Upgraded gearing (pinions & spurs):
1st gear
54/20=2.7x2.5=6.75
2nd gear
48/27=1.77x2.5=4.44