Evan, that's good info, i'll look into trying one.

The problem was that, to start with, the motor i'm using is a high torque (thus low kV) motor. It's really meant for plane use and not heli use.
The second problem is that Century uses a very strange pinion module and I can't find anything bigger (i.e 26 or 28T) that will match it. It never occurred to me to check for a bigger spur.

Thanks for the tip on the gear. I'm going to see about ordering one. As it is, the head speed is not terribly low, but I certainly would not mind it being a bit higher .