What kind of BBs should I use for my airsoft rifle?

It's a UTG M324 Master Sniper (Gen 5). It's supposed to be like 450 FPS with .12g BBs, and around 315-325 with .20g BBs. Now... I was wondering, since it hops up like crazy with .20g BBs, should I get .25s or .30s? On Amazon, everyone says .25s work great (I got it off of Amazon), but with the insane curving it does with .20s, I kind of doubt them. Now I'm wondering: would .25s be enough, or should I go a bit further? Thanks in advance.