Get rid of bandit mastery on GP
It's strong, it fits his thematic as a pirate, but it's frustrating to play against with how much gold generation he already has with his Q farm.
Also, if you remove it, Gangplank could be up for some compensation buffs if he falls out of the meta someday. (Which he kind of has, but he's now really an A- tier champ instead of S+ tier)