Well I see you don't have an answer to your question asked nearly a year ago. Well, I don't have one for you, but what I do have is similar to yours in that when I hit a relatively high speed in combination with wind, there is whistling/howling sound. It sounds like the wind if hitting some small pocket near the meeting point of the upper front windshield and upper front passenger door. Very odd & does aggrevate me, but its only when the wind is blowing and I'm running average highway speeds.
My hopes is that you finally found an answer, probably elsewhere other than this forum, and could update me on that find.
Thanks,
Chas