Yesterday we were flying on a long cross country. My friends plane is RV-8 mine is an RV-6 both Hartzell CS with Lyc. 360's. Manifold pressure 22.1 RPM's 2450. We were .3 miles apart same altitude. (8500' on a heading of 192) My winds aloft were showing 355 at 37, his were 020 at 41. Both units are 4500's and we had exactly the same GPS ground speed of 212.

Trevor or Rob is this a calibration issue or static error in my plane? We flew exactly the same course on auto pilot, we were never more than .4 miles apart for a 2 hour trip. The ground speeds never varied from one another, but the indicated winds direction and speed were never the same.
I checked the winds aloft on XM weather but the arrows are not degree specific.
I know my IAS is about 10 knots high, so my TAS is also 10 out. Is there a settings adjustment for this in the EFIS?
Thank you for your help.