Can I run my Traxxas model at the same time as my friend who also has a Traxxas vehicle?
Yes. If one or both of your models is equipped with the TQ or TQi 2.4GHz radio system, you can just "switch on and drive." The TQ and TQi 2.4GHz radio systems automatically locate and lock onto the receiver that they are bound to.
If you are both using the AM TQ radio system, you will have to make certain your models are not on the same frequency. There is a crystal in the transmitter and a matching crystal in the receiver onboard the vehicle. These crystals control the frequency that your vehicle uses in its transmitting and receiving of its signals. As long as your two radio systems are using different frequencies (different color crystal sets), they will not interfere with one another. Traxxas offers six different frequency crystal sets for its radio system. If you and your friend happen to be on the same frequency, you can purchase a replacement crystal set for your radio system so you can run your models at the same time. The part number to order would depend on which frequency crystal set you need.
Note that the crystals are labeled TX and RX on their tags, as below. Install the TX crystal in the transmitter, and the RX crystal in the receiver.