HPC (high performance coatings) is located just a few miles from my home. I went to the "trouble" of getting my downpipe coated when I received it. It is a great mod. While I had the downpipe coated, my father who is an avid Toyota Landcruiser fan had one of his V8 exhaust manifolds coated (the other was being replaced at the time). After he installed them, when took some temperature readings of the two. The coated manifold was about 120 degrees cooler than the non-coated manifold. Anyone who has spent time around V8 converted Cruisers knows of the overheating problems they have. This was probably the single-best upgrade (cooling) that has been done so far.

The one thing to watch out for is that all of that heat comes out of the muffler and not the radiating thoughout the exhaust system. While this may not be a bad thing, it could (probably wont unless your muffler tip sits just behind the bumper) melt a bumper.

In short, Wraps and Thermal Coatings are a good thing.