[Thenorm]

i tip my hat to you, u absorb the subject matter well. My all encompassing statement about convection was mostly for the engine bay and the cooling system which are around 100°C. when you get upto 1000°C at a cat converter, radiation will play an effect. I guess that's why they put heat shields on it.

Maybe that can be our rule of thumb. If there is a heat shield on an item (like muffler and cat), then you need to manage its radiant heat