I wrapped the exhaust manifold on my turbo ZX10R engine using Thermo-Tec Generation II Copper wrap and it has gone all dry and brittle and began to fall off, after only a few hundred miles, not overly impressed with that! Although the downpipe/exhaust are still fine.

It worked wonders for the under bonnet temps though, the wrap felt like a household central heating radiator when the engine etc was at full temperature.