But the solution is simple. Just tilt the motors in a angle of 3 to 10 degress. With my homebuild motor mounts this can be achieved very easely. Just add some washers on one side of the motor mount. See the image.
This simple solution gave my new frame a real yaw authority boost. Now it's more stable then my quad + frame on al axis (yaw, roll, pitch) even altitude hold is much better. So if you notice pour instability and bad yaw authority. My advice: tilt your motors!
And here is the video of my first flight with my new quad frame and tilted motors.