Hey guys,
I have been running the 1.944444444 (LOL) ratio for several months now. I happen to use the 3racing pulley set which comes with a 16,17 and 18 tooth. I had some custom belts made for the car so I can't comment on what existing belts to use.
Canyon-Changing the internal ratio allows you to have a different spectrum of gearing options. Using a taller 1.944 you don't have to run a 60 tooth pinion with a brushless motor in order to reach your desired gearing.
Some argue the car will accelerate out of corners with a lower internal, but I find the difference to be negligable. The math says a lower gear comes out of the corners faster, but you will hear conflicting reports.
Overdrive is a term used to indicate that the front wheels are spinning faster than the rear. With your front wheels spinning faster than your rear wheels, the car will seemingly have more steering.