You beat me to it Mac I was thinking the same thing.
The principle being the exhaust wrap is that it's cooler to the touch and runs hotter internally as mentioned. The hotter internal heat supposedly helps with the burning of (I can't remember the term) excess vapors in the (scavenging, that's it) It burns off the excess left overs that get wasted through the exhaust system instead of wasting it, it gets burned off. This in turn supposedly gives a bit more power. Whether that's true or not is debatable.
The downside to exhaust wrapping is that it's tricky to apply as it don't stick and is held with wire wrapped around it, to hold it in place. You would need the headers off to do a good job. Also it's believed that the moisture ie. rain, salt etc absorbs into it which aids in the speeding up process of corrosion.
As Seb said it's more of a Yank thing, check out the Superhawk forum, loads of info over there.
Have Fun.
(:-})
) or is it some thing that could and indeed should be "looked into in depth" Many thanks guys 
a little too quickly for my liking! 
