15,000ft as I flew over the top of Pikes Peak, 14,110ft. Only 890ft AGL.
https://www.youtube.com/watch?v=cTYV3BZCQVkBut it took some ridge wave work to get it.
The jabiru pretty much didn't want to give me anymore.
Gary Motely did a lot of high altitude work in his Aerovee powered sonex.