Post, the most I've seen with my stock Cat's is 900*F. I've seen 1100*F post in a Maxidyne powered Mack, which by the sticker on the pyro was the max for that truck. The standard in post reading trucks as I was taught is drop a gear or 2 if the temp is over 900*F post. This may be cause taking the readings post turbo are slower. The maxidyne was rated for higher temps but it ate the tops of 2 pistons too.
Highest I've ever seen was 1280 heading up the Cuesta Grade, Northbound 101 - the steep side. I was holding 55ish mph at WFO, Six-Gun on level 3. Backed off just a hair, to maybe 15/16 throttle and the EGT's came down to 1225ish, settled at 52mph. Highest I'd go, well, I talk big and say 1300, but I wussed out backed off at a steady 1280 in the above situation. If I get a new Wastegate actuator, I think I can bring EGT's down a bit and power up. I have 5 more psi that I can safely pull out of my turbo without worrying about longevity...
I usually run 900* pulling my truck combined weight of 15,000 lbs on the flats. Pyro is pre turbo. On a long uphill I drop into 4th running high rpm I can hit 1200 but back out of it just a smidge and can control them pretty easy. I have read 1250 is redline but can go over for short periods but I try to limit to 1200.
1350* pre turbo is the max safe, sustainable limit. You can go higher but not for very long. Shoot, I can peg the 1600* gauge in my 94 if i'm being stupid but that is only for a few seconds! I always try to keep it under 1300* when towing. CTD's should always have the EGT probe mounted pre turbo because post turbo readings on this motor can range from 200-400* cooler than pre turbo.
