Wetwilly, from your explanation it sounds like you had dual exhaust out the back but the donut disintegrating cause the problem. I still can't understand this. Could the engine's excessive heat have been the culprit rather than the disintegrated donut? Other than the valves was there other damage? I hung around in my brothers shop where he built racing engines for over 30years (doesn't mean I'm any smarter though) and we seen a lot of strange things, and some not so strange, on the dyno and on the track. Just curious of all the other damage.
