Bizzy's Booby Rubs scene has special dialogue if Steele has Hyper Large Z Cups or larger (194).
Tank Kannon probably has the largest penis of any NPC, but you can't interact with him. Steele can go larger with exploits.
I don't think Nessa technically has a cumflation limit, but it effectively caps out.
Brynn explicitly maxes out oral cumflation. Not sure why it's not a static number.
Most hyper scenes have a lower bound, but don't really take into account anything too far about it.
