Quadcopter Progress

Well I have recived my new Lithium Polymer battery and have been working on my quadcopter some more. I have one axis tuned and working fairly well heres a cool Youtube video of it working:

Currently having a slight issue with the other axis, when I first turn on the PID loop one of the motors shoots off in one direction and then after a bit it gains control probably due to the integrator kicking in. I don’t think there is a software problem, since the code for the two axis are the same. I’m wondering if there are some tolerances in these motors which would cause one to be stronger than the other, maybe the Kv (motor velocity constant) of the motor is significantly different between the two.

Andrew