why insulate wrap exhaust crossover?

If the goal is to have a lesser intake air temperature, why not wrap the intake duct instead? (and have less radiant heat actually enter the duct?)

Has anyone done this with success?

i am going to do this when i take my heads off and hopefully it will do a lot of good not that its not a good idea anyway

I was told the hotter the exhaust the more faster the exhaust will flow, thats why people heat rap/tape there headers. correct me if im wrong, but it makes sense to me. science crap...