Wish I had of done this had several opportunities . I have to say on my Subarus its hard to tell without measuring due to the Headers being underneath. I know on the Patrol under bonnet temps were massively less , Like from not being able to put hand anywhere near manifold to being able to hold your hand an inch over it .

When I had my 1600 with the FJ20 my high mount had the dump pipe wrapped and a beanie , my paint cracked on the bonnet from the heat .

I got the turbo and manifold done coated at CIC and repainted the bonnet . The dump pipe was still wrapped and I put the beanie on still but had the car another 2 years with no issue to the paint . It cracked originally after about 8 weeks.