Thanks for the link, I read the "test report" closely and of course I have more questions, for which I don't demand answers. Not denying in any way that those coated headers look da bomb. There, I've said it. After that...well, I did say I had my engineer hat on.
The report says steel tube samples were coated and cured. It doesn't say they coated inside and out, just out, or just in. Are we considering the effect of one-sided coating or two-sided? Can't tell.
The results show the pipe sample with 572 degree gas flow will still be 524 to 462 degrees, the 1112 degree flow will be 1057 to 1010 degrees, and the 1706 degree gas flow will be 1625 to 1521 degrees. The 'net says aluminum (as in your cylinder head) melts at 1220 degrees but depending on the effectiveness of your cooling it may be okay to run hotter combustion chamber temps. I have read that the 2002 turbo has an EGT gage and it's good to back off before approaching 1600 degrees.
The heat test ran for 10 minutes but the report does not state the condition of the coatings post-test. 10 minutes is a blink of an eye for a car that's ...decades old. Nor does it note whether the solvent-dipped samples were those that were heat tested.
The solvent exposure testing is useless unless one wants to splash any of those on your pipes. I won't.
Ignoring any non-tranferable effects between the test and "reality", what is the good of running these header temp differences? None of this substantiates that these coatings have auto application other than for looks, which might be obtained more simply (and temporarily) with a rattle can. The report did not advise or recommend actual use of these coatings, other than to say they are "exhaust coatings".
Anyone want to link something to the effect that these thermal coatings somehow provide benefits to gas flow? Apparently they keep hot gas from losing some heat in transiting the exhaust tract... but is there a benefit? I'd think header wrap would do this as well...