Blue pipe

I rebuilt the nephew's YZ144 recently and have been dialing it in.
Running VP110/pump mixed with K2 40:1.
Playing around with the jetting and kinda going a little on the fat side with a 440 or 450 main.
Piston top and underside look great. No signs of detonation or strangeness. The thing rips
and runs clean.

I will say the squish is a hair on the tight side and right about 1.02mm. I'll open it up to more like 1.1mm
when I reassemble it this time. (opinions on squish measurement welcome, too.)

What worries me before I hand it back to junior is the pipe just looks cooked. This was Scotchbrited clean
before riding this morning. Am I tripping or does it look like it's heat-blued? Do pipes get like that? I'd hate to give him the bike saying it's good to go and he cooks it or something.