JetHot might not be cheap; but it's unequaled in durability and heat transferred. I would NOT spend the money if the pipes are dented or badly pitted. But the coating is tough as nails and coats both the outside AND inside of the pipe. If the pipe is in decent shap and original, especially if it is hard to find, I think it would make an excellent investment.If you look in a phone book you might find platers in there under chrome or plating. You can also sand and paint them with header paint for cars with good results. It comes in black, white, and silver. Sand the headers good with 220 grit paper until smooth but not mirror shiney. Follow the directions on the can to the letter. Run the eninge at idle for 15 minutes with a fan in front of it to cure the paint. Don't rev it. it will smoke and stink until it cures. BBQ grill paint works too.
You used to be able to send stuff to Jet-Hot coatings to get it coated. It's not cheap. http://www.jet-hot.com/