http://www.rccaraction.com/blog/2011...oor-nationals/
Scroll down to "Brent AE B44 wing tip" for a video where Brent Thielke explains the mod.
Too bad the quality of the video is one of the worse I have seen in quite a while. But at least you can hear the explanations and luckily there are pics with good quality of the mod like the one posted in this thread of Maifields car.