It's an invisible wrap...  Picy no worky...

Looks like the stuff they use to wrap a cast.

I seriously doubt you would ever be able to measure any performance difference with a wrapped pipe, on the relatively low-performance LS640/S40 engine. You are making a fashion statement. Even if the moisture that may - or may not - be trapped doesn't cause rust, the chrome WILL turn blue from the extra heat.

Had some rust on chrome saddle bag holders so I tumbled them first then powder coated black.  Everyone that has seen them has had nothing but compliments on it.  I don't know if it would work the same for the header.