Colbalt SS header glows in 1 minute

I have a friend that has a 06 Colbalt SS that is stock.He's been trying to get it going for a while now.It started to run pig rich when he started it one morning .From what I'm told,it's not showing any trouble codes,changed a bunch of sensors(i can find out which ones).
And when it's starts,he lets it idle for a minute or so,he has to keep his foot on the gas pedal .the exhaust manifold starts glowing......He also recently changed the manifold to a header and a aftermarket cat(only mod.that he did). Same results.I haven't had a chance to check it out up close.Anyway he's thinking it may be the ECM that is fried,but I downloaded the ECM file with no issues,and can read it no problem.I'll check it out with my scanner and also log with HP to see if I see something weird.
Anybody seen this before,any suggestions ?

Thanks in advance.

Only thing I can think of that would make the header glow like that would be a ton of timing retard. I cant think of anything that would fuck up timing that bad and not throw a code. Maybe the crank position sensor is bad/confused/semi shorted/not plugged in all the way/likes the color pink.

put the stock manifold back on.

ummm im just guessing but a bad cat will cause detonation which will cause it to run rich because its not burning all the fuel. My 85 celica with a 22re did this because of the cat so just throwing it out there it is possible.

When I had my cams in it would pull to -5 degrees of timing. I had it running for a few minutes and the header was red, I tried tuning it out but couldnt get it to want to run at normal timing so I switch back to stock cams and runs fine now.

Could be a plugged catalytic converter, or extremely rich condition. And extremely rich will plug the cat in the long run too.

Most likely running too rich. Either a stuck injector, bad tune, bad plugs, bad sensor was the original culprit but now could be a couple different problems.