The first name people bring up is Cary Kolat. However, recently I saw his Dapper Dan match and although it officially ended in a draw, everyone knows he really lost. Regardless, the draw makes his record not perfect.
Then we have Scott Winston, who did win every match but missed the last half of his freshman year because of injury. In my mind, this doesn't count.
I've heard through folklure that Dan Gable was undefeated in high school. If this is true, is he the only guy that has reached perfection during high school.
Nick Suriano is pretty darn close with 3 Beast of the East titles. He did lose to Spencer Lee, but that was not a high school match.