I've seen MJR bust out multiple sets of 5-6 very strict pull-ups at 290, and he's witnessed me do the same. I'm down to 265 now and just yesterday hit 11/7/5/5/5.
That said, Mark Bell also just posted a video of KK block pulling 940lbs at 279lbs, without a belt, and sumo for the first time ever. Absolute freak, even if he does do kipping pull-ups.
Obviously as everyone mentioned, they are not strict form pull ups.
Should say 55 Kipping pull-ups. Either way...that's hard. Try it out and see if you can do 55 straight using the kipping technique.
EDIT - just went through the thread.
Yes, kipping. Strength and Endurance. Still very hard.
It actually takes quite a bit of air to do kipping pull ups.
Butterfly kips take even more air and takes a while to master.