header wrap? pro's / con's

Well I wanted to just fully wrap the headers for the reasons I read people do it for keeping the heat out of the motor compartment. I end up wrapping the passenger side in the oil filter area to keep the heat off of that and I wrap the driver side where it touches the milodon oil pan to keep the heat off of that. So now I'm just thinking wrap the whole damn thing before I even put them in there. Of course they're my favorite cheap Summit headers.
Of course for every up there's a down so I don't know if getting the heat out of the motor compartment is going to put it back into the motor and have adverse effects there? I'm trying to get heat out of the motor as the motor will be to taken from the 100ll that it's always been ran on to regular 91 octane gas. I guess the last thing I want to do is create more heat in the head.

The idea is that the heat stays more in the exhaust and exits through it instead of hanging around in the engine compartment.
It doesn't make the engine hotter anywhere.