As stated earlier, balloon bust in Tulsa, OK, Denver, CO and Topeka, KS. We use no barrier. The best balloon bust we used to run in KC was when we used the F2C circle. 5 balloons on the circle perimeter. Take off and fly 7 laps for speed timing. Then it was break the balloons by passing over the first balloons and breaking last in line. Speed times total number of balloons broke decided winner. 2 balloons at 90 MPH would get beat by 3 balloons at 70 MPH. Anyway balloon bust is a spectators event. DOC Holliday