George, I have issue with the header wrap on my daily drivers. On passed hot rod cars (Insert drivin in nice weather only ! ) I have not had a problem.
Freinds of mine that race cars, use the wrap on love it. But they also replace parts often and if and when it comes to the headers, it's nothing but a couple of pennies to them in the big picture.
My advice is to wrap the section of pipe needed to sheild the starter at most if the car will be driven in all sorts of weather. This way, the wrap will not soke up the water and rust the pipe.
Then, spray/caot the wrap with a high heat paint to help form a barrier on top of the wrap. This works peerty good and should last a long time. Thermo Tech has such paints.
Do not cover coated headers with the wrap since the wrap holds in heat and can break down the coating and pipe with excessive heat being retained. The constant heat cycles can wear down and faitgue the metal at a faster rate than normal. The pipe will crack leaking exhaust gas.
From the been there done that camp.
