I remember last year that heading was allowed during summer tournaments, but outlawed at the beginning of fall season (SCDSL), along with the introduction of the buildout line. Who knows how they'll interpret the rule (not consistently apparently), but IMO the rule should apply for the entire age division. U11s and below no headers, everyone else fair game.
Actual age would seem to be the defining factor, so 2006s are 11 until Jan 1, 2018. But not many of Cal South mandates are clearly defined and consistently implemented...