OP asked about TTI suggested about preventive use of WD-40, and that is all but ignored in the replies here so far.
No offense meant but I'm guessing it's being ignored as it sounds like pass the buck BS, to me anyway. Having owned a classic car resto/ repair shop for 25 years the only coating that has held up over time is Jet Hot or VHT. Believe me, we have tried many. The manufacturer applied coatings are a flat rip off IMO. One is lucky if they hold up more than 1-2 years in the collector area and near the exh ports
The biggest issue with Jet hot is you have to (should) buy the headers, do a trial fit (STRONGLY ADVISED), then ship them to JH and wait for them to come back. By the time you add up all the shipping and time it's quite costly. BUT they have even stood up to dyno break-ins without discoloring a bit
My next choice as previously mentioned is the VHT SP117 flat Aluminum. When properly applied to a sandblasted surface it lasts.
About 10 or 15 years ago Jet Hot tried a program in which you gave them the MFR. & part #. They would get the headers, coat and ship them to you. great idea as it saved a lot of time and cost. Didn't last due to fitment issues and customers wanting JH to refund the $$
