882 peak watts for a brief interval is not unusual... ran some old fashioned calculations a while back and calculated that at my weight I was able to generate 1000 watts for a few seconds and this was when I was topped out in a sprint or hammering up some short 12% grades we have here and a 20% grade is going to bump up the numbers if you were laying down some crank bending power.
As another smaller rider my wattage numbers are lower and bigger guys can really generate some intense, albeit brief bursts of power... am thinking that track sprinters get numbers in the 1800 watt range.