The first thing to find out, is whether the thermocouple (temp probe) is mounted pre-turbo or post-turbo. From what I understand pre-turbo temps can be up to 300 degrees hotter than post-turbo.
My thermocouple (on a 6.0L) is mounted pre-turbo and the person who installed my pyrometer (Ken Imler of Imler Diesel in Sacramento) set my pyrometer alarm at 1300 degrees. Had an '02 F250 with the 7.3L, and the pyrometer was pre-turbo, and I think the alarm was set at the same temp, but I'm not sure anymore.
Hope this helps.
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