What temp does the exhaust pipe reach?

Trying to determine what temperature the exhaust outlet on the 912iS reaches because I'd like to add heat shielding on the inside of the cowling where the pipe exits. I know my EGTs see 1500F, but by the time the exhaust passes through the headers and the muffler and into the final pipe, I would have thought it would be significantly cooler. But given some gold heat shielding I tried that's rated for 850F completely melted through, I'm trying to determine what the actual temp is. Does anyone have this data?

I can't even think of a way to test for this because even if I did a ground run at 4k rpm and then hopped out and pointed a temp gun at the exhaust pipe, it may have cooled significantly by the time I was able to reach it. Also, I fly at 5,500rpm not 4k. Although there's a lot more airflow while in the air. Also, can't do the test with the cowling off on the ground because the exhaust pipe will probably be significantly cooler with the cowling off than with it on and all of the radiant heat. So I just cannot figure out how to find out what max temp the actual exhaust outlet reaches.

I'm talking about part #2 in the below graphic.