I understand Jinx, but I've never seen a single wall header on a Triumph that wasn't blued from the heat. The reason for the double wall headers was to not have blued headers. On my '71 Triumph, I had less restrictive exhausts (megaphone style), re-jetted, and tuned. Nothing could stop the headers from blueing.
With the double walled headers you can definitely avoid blueing with the engine properly tuned and set up. Some still blue that are running too lean and/or still have the AI installed.
