If you're getting 300-400C up hills then your probe isn't working. It's either in a cold spot or there is something badly wrong. Even stock diesels get around 600C at full load.
I'll admit my probe is really only monitoring one cylinder(#6). It was more convenient for drilling than the middle.
As for Temps I was referring to cruising and maintaining hills. Not full load. It can reach 600 but because of my probe location I try to stay under that.
If I actually maintain full load in 5th, it's usually speed scaring me before EGTS!
I don't think these trucks should be capable of 100mph. I'll never know it's true top speed.





