one quick test...it's normal for the nose to swing left as you spool up...that's because the main rotor blades are turning the other way...pull your motor wires, hold your heli in your hand and quickly torque the nose left...the tail servo arm and pushrod should move forward, thereby increasing pitch on the tail rotor blades to resist the torque...even without mods, the amount of pitch in the tail rotor blades (spinning over 8,000 rpm) should stop any yaw...ken