OP above are all great ideas to customize a Glock. They're like hondas you can do a lot but the 42/43 are slightly more limited than their full size companions (RMR capability or RDS) long extended magazines etc. The guys suggesting ammo and range time, that's never a wrong answer, and if this is the only gun you own and you aren't trained well with it that's time and money better spent. That being said, your question was what can I do to customize a G43, the answer I found out with my similar G42 was a **** ton, still expensive, still a Glock, still a .380 but HEY still America too, dress it up pretty if you want, I did!