help with pinion suggestions

[B3nchy]

hello...

completely new to competitive RC racing and am looking for some help with setup. i have:

Team Associate B44.3 running a Speed Passion Reventon-S ESC, 7.5T speed passion 3.0 motor.

The spur gear is 81 teeth.

what size pinion would be a good place to start?

sorry im not sure what info is needed

[dodgydiy]

i ran a 22 tooth pinion on a v2 speed passion 7.5 in an old b44, worked ok for me. dont know if the diff ratio is the same on the bb.3 as it was on the b44 but i suspect it is