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.
I vote for this as the best answer.
On a directly related point, I would add that as the temperature falls going toward the rear exit, so does the pressure. As the temperature and pressure decrease, so does any benefit decrease when trying to improve the exhaust system. Likewise, decreasing the pipe diameter slightly near the tip causes no measurable loss of power, which the factory did with some exhaust tips.
