[Rick Parker]

I think it has to do with Exhaust Gas Tempratures. Any of them can be made to run lean an thus hot to varying degrees
if the A/F mixture is incorrect. With under car exhaust, there may be enough surface exposure to the point that much of the heat is dissipated by time it reaches the rear of the car,??? Sort of like touching one of the header tubes and then the tail pipe, there will be a significant difference. Under the hood of mine it was necessary to use some pieces of reflective insulation in the fender liners and under the fenders themselves to protect the fiberglass. My headers give off a lot of heat.