I don't know if you are using the crossover dual exhaust system like I am but if so check your cowl under the left front cylinder where the front crossover pipe makes the bend to start rearward. Mine gets mighty hot in this area. The aluminized woven silica (expensive) from Aircraft Spruce bonded to the cowl with weather strip adhesive works very well as a thermal barrier and reflector.
Sorry for the delay in answering. I did not build my RV; it was built sometime in the '80s. I have no idea what the original exhaust system was, but the Vetterman replacement is definitely an improvement. The 6 has a thousand hours on it, 700 are mine. The original exhaust seemed to have failed because of a poor support system.
Armondo