From what I am reading from guys who have/are sailing with the Stealth system, it appears to me that they perform much better with stronger wind (greater speed) and have a far less noticeable effect in the light?? To me that would indicate that the working surface of those foils could be a "little on the small side". We had a similar effect with smaller foils early, and it was only after I did some recalculations and we enlarged the foils that an appreciable performance improvement was documented throughout the full range of speed, BUT most dramatically in the light (and particularly choppy)