I just talked with Clinton at Race Coatings. He said the Swaintech is an awesome coating but has a course texture and will retain every bit of dirt and grease that gets on them. Impossible to wipe off. In that vein, ALL white coatings are going to stain from any oil and dirt, because of the color. He can ceramic coat them, which for white is a 4 stage process, for $300, BUT he says you should wear gloves for install and anytime you need to touch them. The coating will be smooth. And never use fresh coated headers for engine break in or dyno. The coating should be cured with a few short drives with normal heat cycles.
I remember the staining as an issue on my appliance headers in the 70's too.
