As I posted above, I got 998SP off a single kill doing a leve I was significantly underleveled for, so it seems the cap is removed for leves at least.
It's probably removed for normal mobs too, except that in current situation it seems impossible to get 500+, so I don't think we can confirm this at all unless maybe like a rank 1 killing some 50+ mob...somehow.
I don't get this system at all, kill a yellow(at 33), get 110, kill a red, get...86?
Something I'm speculating is they implemented this new system without removing the old "you get less SP as your rank goes up" mechanics.
Because killing a red at rank 10 will give me 300~
Killing a much higher red at 33....86