What may beneficial is the interior ceramic heat coating.  I had it done to the exhaust when the plane was finished in '99.  Does it help with cowl temperatures?  Never flew the plane without it, so don't know.

 

For the exterior of the pipes, the coatings seem to stick better to mild steel pipes than stainless steel material.  Mine along with every other set of aircraft stainless pipes I have seen have lost the exterior coating, especially in the high heat merging joints.

 

I have my pipes done at the NIC (Northwest Industrial coatings) the company that manufactures the materials for the industry.

 

Gary Edwards

LNC2