Conditions?

Whenever water is not dripping out the tailpipe and no “fog” seen then it is above 212 degrees F.

Full throttle for more than 60 seconds on a hot summer day while overtop blacktop pavement?
1000 F at the exhaust manifold declining to 500 F at muffler outlet to 350 F at tip.
If the tailpipes are extra large diameter like 4 inches lower above numbers.
If stainless steel raise above numbers.