Let me add to my comment about wrapping the pipes. Years ago I had some
modified big bore stroker Ti's in my 61 and 71 vans. I was looking in the
yellow pages for some exhaust wrap when I found the number of a custom
exhaust builder. I called him and he had some and said it worked well,
especially on turbots. But, he said if I was going to use it for street use
to plan on replacing my exhaust every couple of years because the pipes start
deteriorating at the header flanges because of the high temperatures. He said
the best for street use was the HPR coating which covered the inside and
outside of the pipe. I finally settled on aluminizing my exhaust which
dropped my head and oil temps to where I was happy. The theory was that the
aluminum coating radiated the heat off the exhaust quicker. Besides, it cost
me about $90 and 1 day. The HPR (then) was about $300+frt both ways and 7-10
day turnaround. If I had the time/money I would have gone with the coating.
It might be interesting to see what the RV guys are doing about the problem
or what some of the header mfgrs like Hooker, Doug Thorley, and Jardine say
about exhaust wrap? For the industrial/aviation use of wrap I would bet the
part being wrapped is designed to be wrapped or is on some sort of
maintenance/inspection schedule.

Ken Hunter
82 Westy 1.9D
84 Jetta 1.5D
89 Mitsubishi van