while a hair gas hungry.. a 901 or 801 are pretty much a 50hp engine machine depending on how/where you measure her and how you have her aspirated and fed... pto hp is a few less.
Now. general rule of thumb is about 5pto hp per foot of mower.
due to weight and size of an 801/901, you generally cap out at a 6' mower max or you get tail wagging the dog issues. that means that on a 5' mower.. you have a built in cushion.. you are likely running 9hp per foot on that mower.
It's also well established that waist high stemmy weeds mow easier than lush grass.
Given all that. it's not stretch to see a large red tiger mowing stuff that completely obscures the tractor.