I don't mean to offend you but I really doubt your horse is 16hh unless the person holding him is REALLY tall!
Have you had a wicket on him? I bought one because I couldn't stand it anymore. Turns out my mare (Registered as 14.2hh) is 13.3hh. My gelding who everyone swore was 15.3 at least, is 14.3. My three year old who everyone constantly says "That is a BIG horse" wherever we go turns out to just be touching 15hh at the end of his most recent growth spurt. :)