My experience with header wrap............
When I bought my pre-lit the first time, it was hot in the footwell, so I wrapped the header. When I bought it back 5 years ago, the wrap was still there. 25 years
It was getting crunchy, so I peeled it off in order to measure for building a new one, since primaries are very small.
SUPRISE it's as good as new, except that it's now got a green hue to it. It's chrome plated, must have been a reaction between wrap and plating
I always heard wrapping would cause a header to rust out, but not this one. Maybe the plating saved it, maybe not. It's also pretty thick gauge tube.
I'll wrap the new one as well, really helps with foot temps, and paint with Eastwood paint