I have recently taken off my wing to sand it down to bare carbon (clear coat was peeling). I have routinely hit over 150 mph on a *cough* track, and when in light rain you can definitely tell the difference. At this speed the rear end with no wing begins to hydro plane MUCH easier and begins to fishtail. Even in the dry the difference is noticeable.

 

Well, the wing is actually FOR high speed driving. I don't even think is has much affect (other than drag) below 90mph.

 

Shark....your right...I disagree with Warrtalon. When I removed my trunk and wing the combined total replacing it with the cf trunk was 17 pounds. Grant it that weight is up high in the rear end...but 17 pounds makes a difference for a variety of reasons.