Harold,
Thanks for the offer. There's no need to spill your secrets. I was just curious.
I am going to try two things this weekend. I cut our the spoiler and attached it with velcro to the back side of the grill. It sits between 1/2" and 5/8" below the grill. That should help prevent air from getting under the body. I also drilled a second set of holes to move the body back 3/8" farther back. I'll try both methods and see which makes the biggest improvement.
Thanks again,
Chris