Oh wow. Thats a good one. I want to know this one too. I've never seen anyone get a speedometer at a high school match and catch some serves. I also want to know whats the average serve for USTA 16's and 18's are... If you all don't mind...
The top player in our county can serve about 120 max on the first. His average first serve was measured in a tournament, it was 112.4. His second serve was about 65-70( being a heavy topspin/kickserve)
i cant prove to you guys but my #1 definitely serves over 110mph for his first serve. and me ( #2 ) my serves are a bit slower. =/ 60-80 mph is really slow =P