I think the documentation on the telemetry and the speed calculation is a broad overview at best. Is there a Traxxas employee that can weigh in on this? The question is if you don't change your garage settings after changing spur and/or pinion will that affect your telemetry speed?
I will try to test this, but don't have a radar gun handy to give this a go. I was figuring to test lock the model and start with factory gearing 46/14 and Make sure the garage is setup for that gearing. Make a speed run trying not to spin the tires and capture the top speed with radar and telemetry. After which change the pinion 46/34 but don't update the garage the speed control should keep the car from going faster then 50 mph on telemetry so also capture that high speed pass with a radar gun. Lastly change the garage settings and do the previous test and then compare the data. Anyone in a warmer area with radar gun that can do this?