They do indeed affect the way it runs down the runway. If they are not installed correctly, they can cause a bank to the right (in my case) just before it has enough air speed to lift off. Mine had a hard break to the right before it left the ground until they were removed. Several people tried it and had the same experience. You could not see it, but it appears they were not installed exactly in the right place causing un-even lift on the wng tips. When the plane was flying, it needed a little left aileron to fly level and that caused it to crab slightly. After removing the devices, the take off was much more predictable and controllable and the plane flew straight. It is possible that they could have been re-installed correctly and not had the problem, but the plane flew so much better I decided to leave them off.