Here is a Directional Gyro adjustment procedure:
Since I can't read well the compass in the Hurricane and Spit, there's a possibility to read it with the label in the tooltip when you put your mouse pointer there.
It is important to keep the plane straight, level and with no accelerations while adjusting directional gyro. In this video speed is slowly losen, but it looks like a slow decelerations does not cause big compass errors like a quick one.
When we'll have the magnetic declination here, we will have to take it into account... (!)