how can i eliminate the high-pitched...
how can i eliminate the high-pitched whistling noise everytime i reach 40mph and up?
Getting a fairing may help with that. It has to do with the airflow over the rack. Any way to adjust how air flows over it may help. I used to have a flat top 6 on my Subaru and having a fairing on the front helped with reducing wind noise.
Check one out here: http://www.backcountry.com/outdoorgear/Thule-Fairings/THU0063M.html
Luck you - they're even on sale right now.
Here is your solution.
It's $15 and really should just come with new racks, but instead it's a necessary additional purchase.