Unless it's race only, any street driven car with it would just be a hack.
#1 Because there is no way to seal it, if it went through any kind of water (even a wet road) it would come in the car and cause hot steam in side the cab.
#2 Even header wrap doesn't stop 100% of the heat. I don't car how well ones A/C works it's like having a heater in your car. Plus that stuff starts to fly off after a while.
#3 Anybody that has ever worked with header wrap knows how nasty that stuff gets when you breath the air from wet cooking fiberglass even when you smell it from under the hood. Not to mention having it in the car.