If you have a windshield what I did was cut a few inches off the top and bottom it did not stop it but it helped a lot. Another thing i have herd of is to put a back on the cab. rocmoc said it will also help to remove the bottom of the dash. Cutting the windshield and removing the bottom of the dash will allow the air to flow through the cab and not create the vacuum caused by the windshield. And did you do anything about the rear wheels?