Originally Posted by Simpler=Better

Fiberglass wrap-I've been using the cheapest stuff money can buy on eb*y on my motorcycle and truck, it hasn't caused the headers to implode despite crazy heat cycles and driving both in the rain. The main trick with the wrap it that you need to paint the manifold below it, and also paint the wrap itself with a heavy coat-otherwise you will have a TON of small fiberglass splinters EVERYWHERE.

On my bike it ended the stoplight overheating, quieted it down, and gave it a butt dyno improvement. The truck's underhood temps are significantly lower-can't comment on power because I changed from an unwrapped cast manifold to wrapped tubular header when I installed it.