ASG-29 Coke Bottle Whistle

I hope some of you ASG-29 drivers have either experienced or heard of this issue I'm having with my 2012 ASG-29. The ship has about 200 hours on it. At about 100-110 knots I have a very loud and annoying sound that comes from the rear of the ship. It sounds just like someone blowing over a coke bottle to create a tone. I can get rid of the sound by applying a little rudder although the yaw string is running true while the sound is being generated. Rex Williams said he thought it was the tail dump opening. I've put duct tape over the tail dump valve and still have this annoying tone accelerating through 100-110 knots. John Murray thought that it was the gap seal tape on the rudder. I would have thought that would have produced more of a buzz sound but this is probably my next step. Hopefully someone can enlighten me as to a possible cause!