During my flight testing I have noticed my EFIS 100 acts much like a compass (with about 1/2 the lead/lag degrees) when turning to a heading of North or South. Just like the wisky compass the E and W turns are ok. I has been my impression the the EFIS should show a "gyro stabilized" turn. I have re calabrated my EFIS using a local compass rose and the headings seem to be right on or very close. I have checked and rechecked my inclination dip. This could be quite concerning when used for instrument or precision turns. Any Suggestions?