OP, I can assure you that if the 566F was on high, full fire box of fuel as described in prior post, the temp you are seeing is quite below higher recorded temps.
Was this directly in front of the flue collar? What device was used to get temps? IR gun? Bimetallic thermometer?
Yes this was directly over the cat. Full load on high. It was one of those $17 jobbers from amazon, maybe not 100% exact, but close enough