Looking to get more power from a Youth size 110cc Atv - the stock carb is the PZ19, is the PZ20 a better carb for an upgrade or is it too much for the 110cc motor?

 

Won't make a blind bit of difference. 1mm in throat size is miniscule. In theory it allows a bit more mixture in at wide open throttle, but if the valves etc, don't allow that much extra in anyway, all it does is drop the vacuum slightly, weakening the mixture.