help with choosing a brushless motor

[Crash]

after another great bit of racing at TORCH today i am now even closer to using the last pair of brushes for my trusty checkpiont - the days of brushless are nearly upon me haha

However having never run with a brushless motor (apart from one race with Dan Browns sx2) i have no idea what turn motor to get - either a 6.5 or 7.5.

what do most of you guys run for 2wd?

Cheers
Chris B