Results may vary but Kooks headers can certainly glow, they are not made of any magic quality alloy that makes it not possible. On my N/A fox 393w combo, I was going to pull a plug after a run down the strip and when I popped the hood, my Kooks headers were neon orange and there was no way I was going to risk a burn to pull a plug.
The fitment of Kooks headers on a fox body straight out sucked in the mid 2000's so all companies have had their growing pains. For the money I paid for them at the time, they were my biggest regret of any of the parts I had on that car. There was a handful of us that bought headers for 351w swaps during the same sale/group buy from Kooks and all of us had fitment issues. Their customer service was completely arrogant and turned me off of their product forever but I imagine they have learned a thing or 2 since then.