Black Y pipe

It’s been kind of slow here at the Panhead Section lately so let me run something past you guys.

I installed a four piece exhaust system on the panhead this spring and have put nearly 2k miles on the bike riding mostly back roads and the occasional short ride on the expressway. The exhaust was still looking like new until this past weekend, when I took it for a 200 mile trip with a friend who owns a newer RK. I didn’t have much trouble keeping up with him, at speeds exceeding the limits, for about an hour and a half, but when I got home I noticed that my Y pipe has turned black over it’s entire length. The strange thing is that the other pipes as well as the muffler look just fine. Is this normal for these four piece exhausts?
-Steve

Different metals and different plating react to heat differently.

Boy do they ever!
I can only imagine that this Y pipe, was cherry red at some point.
The kid has the camerea some where and I can't find it, or I would post a picture. This Y pipe is toasted. It is note worthy that the "Dixie Exhaust" I got is holding up quite well except for this Y pipe.
-Steve