I'm running 27/72 which gives 5.33 on a fairly large outdoor nitro track. Still 2s setup Temps are quite high at around 160f but this isn't too much of an issue. I will be trying my RX8 and 4pole 540 motor on 3s in the future and will probably drop down to 25/72 or somewhere around there depending on how the temps look. I think you can add a couple teeth on the pinion quite safely or alternatively turn up the turbo and ramp settings in the rx8
