I"ve been flying my blade cp for a bit now and I've been using the 8t motor, this won't allow me to use symetrical blades I've heard, I was wondering by going to a 9t motor does that increase or decrease the head speed and what affect does increasing or decreasing head speed have on a helicopter?
Thanks!

Increasing the headspeed will increase the reativeness of the heli. You'll see bigger results from smaller movements.

I found that higher head speed increases the gyroscopic stability of the model to a point. Blade pitch settings will also affect what the head speed is just as much as gear ratio and the speed (kv) rating of the motor. Taking all this into account, if your heli has collective pitch, then a properly set up throttle/pitch curve will result in a head speed that remains constant as you throttle up and down.