Roger - I think I'll end up fitting a metal spiral system, as well as repacking the perf tube mufflers. I'll use stainless packing, rather than the "heat sensitive" glass packing this time....
The stainless pipes look as though they have simply got hot from prolonged high rpm, high load conditions. On the street, they don't get anywhere near as hot as the day at the track.
I have an aftermarket engine management system. The guy that tuned my motor is one of the country's top engine builders / tuners. His main work comes from our premier motorsport category, and the theory there is to run the cars as lean as possible for maximum horsepower, then feed a little extra fuel during deceleration to cool the cylinder walls. I think he's done the same thing with mine on decel, but fattened up the mixtures to cope with the supercharger.
Here's a small photo of Max Wilson (the ex-CART guy) in one of the Aussie V8 Supercars.
