+1 to what ken said, i had the same thing, 80 degree on the standed water outlet sender for the gauge next to the top hose and, about 60 degrees at the back of the head for the coolant temp sensor (getting the readings from the ECU). I would say its always the best way to have the gauge on the hottest side to be safe. when my guage (speco) goes to 100 i know its still safe, even 120 is good but i would stop as its the end of the gauge and you dont know what it could be after that.