I'm presently running a Hacker BL system with a 6 Turn motor.
The things an absolute weapon, but it's sensorless, so therefore it's not race legal. However, I'm not sure where to buy these new as I got mine 2nd hand. Not to mention i think they're close to $700 or something huge when bought new.

Can't recommend these enough. If you're just looking to go fast, Brushless is the way!