Don't know really, I do know these professional tuners know more about setting up a bike than I do...He shoots a good video, but as per previous posts, I have my doubts about "professional tuners"
Takes power away with dropping two teeth on the back sprocket, is technically incorrect. We cannot add or remove power with sprocket changes.
Removing the back brake, ceramic bearings, sprocket change and after all that the bike is a bit slower than before.
Then there is Brock, with motors blowing up using only his exhaust and his upgraded ECU map. LOL, plus grinding brake pads with an angle grinder.
Most of them have quite a bit of seat time and know how to squeeze quite a bit of extra power out of these bikes....
Gearing is the key-way to racing, it is as important as good tires...I don't know about adding or removing power by gearing but you can put the power right where you need it by proper gearing.
If a racer shows up at a track (drag or road-race) and their gearing isn't spot on, they might as well stay in the pit row.