well, I ve already made up my mind, but still the question is interesting, thank you for the provided answer

well, now do not laugh at me please , I have a b4.1 it used to have 6.5t, but was geared pretty low, so if was a bit too hot and lacked power on acceleration. But I really enjoyed the fact that it could do over 80 kph. Then I decided to make it also usable for offroad - have acceleration etc, but I did not want to give up its ability to blow mind of most of the people when pressing the throttle hard so I bought 4.5t lrp octa-wind, when geared for off road, it still goes those ~80, but accelerates amazingly, runs cool. We tried a top speed run this week with different gearing, we really wanted to break 100kph, but (hopefully only) due to people on the runway and signal issues, we ended up at 94 (just one attempt). I was not sure if we can find those 6kph or not, so I was actually thinking about geting something on complete top of the power (in fact, I really enjoy overpowered motor, brutal acceleration from zero to really high speed,..even though it makes no sense for racing, it amazes me and others too). But I will probably stay with my 4.5, add one more tooth to pinion and find better time to use the runway and I hope it will work out. Its a litte project of me and my friend