I guess the only thing I'd call a tic for my DD is the arm flapping. But she has made a lot of progress lately stopping herself. For about a month I have been making a concerted effort to say, "try not to flap, sweetie," and giving her a hard hug. Now it seems like she's noticing that she's doing it.
Maybe you could point out to your soon every time he does it? I'm sure he doesn't notice it at all. Not an angry voice, just a, "try not to do that, buddy." Just making him aware. Or give him a different behavior (a less intrusive one) to do instead. Our chiropractor has taught my DD to press her palms together, hard, instead when she realizes she is stimming.
Goodlicorice (hijack--your username makes me laugh because I hate licorice! and your real name makes me do a double take because my DD is named that and I'm always trying to not type it out here in cyberspace, LOL), my son does a high-pitched yelp a lot as well.... I think it is kind of a defense mechanism, to let off nervous energy and also give him a minute to process whatever he's reacting to.
On the bright side, he used to head-butt all the time, and since we took him to the chiropractor, he hardly ever does that anymore. Thank goodness! Did anyone ever say if they've tried chiropractic before?