They get faster the less turns you have...
...but it depends on what your using it for.
If you doing any sort of club racing or any other sort of serious racing, then you really don't want anything 'fast' as such in a 2wd. I use a Novak Ballistic 8.5t in my 2wd at nationals and it's in no way slow! It's easily fast enough if geared correctly whilst still being controllable and consistent during a race.
In a 2wd a FAST motor can just be pointlessly difficult to drive, and will only make you crash faster and harder...unless you don't mind that and are just bashing and going for all out speed anyway, in which case it doesn't matter...just don't then take it to a club and expect to be competitive lol!!!
And if you relatively new to RC, then even better to stick to something a little slower again until you have a handle on controlling it better. I ran a 10.5t motor when I started club racing, and once I could get around as quickly as the motor would allow and consistently without crashing badly for the 5 mins, only then did I go up to a faster motor.
Anyway...Enjoy
