I tried it with the cover off for a while and noticed why such thick insulation under the cover?probably for protection against something breaking like heater or radiator hose and you have to take consideration that the fuel line and fuel filter is right in front,so i put the cover back,you could remove that thick piece of insulation and add a heat shield on the engine cover just like they have already done so on the bottom cover and probably see some lower IATs,just my 2 cent.