You need to get 100 kills with any spit in any game mode to get the XVI.
After the patch it will be 100/5 = 20 kills with any spit.
If you allready have 20+ kills when the patch comes out, all you need to do is get 1 more kill, and get unlock the XVI.
Btw, it does not outperform the other spits
, the other spits turn better. It is most likely the people flying the XVI, that outperform