Gearing question

[philipalli]

well i own a stampede and soon will be getting my brushless system.

i'll be running a 9920 and 10s on 6-12 cells

when i first get it i'll be running 6 cells (untill i recieve my swami bar)

so what would be ideal gearing on 6 cells

and what would be good gearing for it on 12 cells

PLEASE NOTE: i only have :
18 and 25 tooth pinions
78 and 84 tooth spurs

i also have the stock gearing