Exhaust Manifolds

I think they have chrome box confused with the race only Gold Box ( gold boxes are not just gold, but have a diff look as have fins to help cool)
I ran chrome boxes years and years no problem same as you. The gold supposedly heats up. I never had that problembut my use was short lived as went back to chrom.
I have some new- old stock orange, chrome and gold I tried one of the gold and never saw a difference in my app it is rated above what I needed. So switched back to chrome. Did not want to chance damaging it.