Just thinking out loud here, but for reasons of cost savings and durability, would using aluminized steel be a viable alternative in fabricating headers? This vs. SS for cost savings alone, I know that Aluminized will rust eventually and does not have the added corossion benefits of SS, but will definitely stand up much better than mild steel. Regardless of my choice, It will be JetHot coated.

 

If you're going to JetHot the finished product, just use mild steel; it's way nicer weld than aluminized. If your TIG machine has a pulser, I've found the aluminized welds a little nicer if you pulse it around 60-70Hz. It seems to help float whatever crap is left on the tubing to the top.