If it's in the budget, then buy of have coated. If you have more time than money you could also try a DIY coating like Chromex. Has to be baked and polished.
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Polished ceramic coatings are NOT a DIY process if you don't have access to a vibratory polisher to finish them properly. Even if you have the ability to thermally clean the headers, blast them with the appropriate media and bake them at 500F 700F for a couple hours. If this material is not burnished / polished properly it WILL rust fairly quickly in addition to looking fairly dull in comparison.
The reason for this is that the dull outer skin is still very porous as it comes out of the curing stage. The primary function of the polishing stage in reality is to beat the surface down and close all the pores as well as providing a polish. So merely polishing the skin off this material with steel wool and or aluminum polish doesn’t address the primary polishing function. You end up with a header that is the equivalent to one that has been overheated and starts to pin-hole with rust blisters. Further, using steel wool to polish ceramic coating SCRATCHES the hell out of the most vulnerably part of the header, the aluminum skin. The "polished" skin on these headers that give you the chrome appearance is only about 1.5 - 2.0 mils thick so its very easy to scratch or polish through.
Yeah, I get what you're saying and won't dispute it. I didn't say it was ideal, or easy, or that the results would be perfect, or be at the level of a 'professional' - only that headers could be coated with a product such as the one I named. My bad. I had access to the right prep tools, a large PC oven, (no vibratory tumbler but paper, buff wheels and compounds) and, under the circumstances, got the results I expected. Although they have dulled some with heat, there's been no pits, peeling, or rust since 2012 - and that was after removing an old coating. They still look good/decent - better than paint.
I was under the impression the OP was interested in options. I presented one - without any warranty.
Use someone who's been in the business for decades, and stands behind the quality of their work.