So you were using the ME-51? What cable were you using? Now that I am remembering, I think there are different kinds of microhphone extensions and you need to specify two channel cables. Can you post a picture of the cable end you are using? I will do the same when I get home.
Also, during my wind-noise testing I found the quietest place to be the bumper just below the trunk lid.
I will when I get home. I'm not sure what it is because a just went to radio shack and asked what they had for mono extension cables.
I was going to try that location next time I setup the Gopro.