i have the same chassi, well mine isnt stock no more but it is still a TT01R

gearing depends on the motor and what u wann do with it. with drifting you rather have more low end power then top speed. Heat is you main worry with gearing, as long as the motor is not getting hot enough where it will burn you your gear is fine based on if it gives you the performance you are looking for

the stock tt01r set up is the 22/61 gearing which gives alot of low end power with so so top end

by dropping the spur size u will lose low end power but gain top speed, which isnt ideal for drifting, i would say if ur not trying to go faster leave the stock gearing