Paul,
         When I dismantled the engine, all of the exhaust ports were solid carbon at the initial pointy end of the opening for at least a 1/4 inch to 3/8 of an inch. It was so solid that initially I believed it was just part of the exhaust.  Is there any way of stopping a repeat of this??  Should I grind this opening a little deeper of just forget what I saw??   I believe the motor had 20,000 KM on it when removed from the car.
   Neil. In NSW Australia

Please take some good pictures of that and send them to us first.
I have heard of that happening with engines that have been babied.
AKA never driven using full power.
Is it a four port or six intake port RX8 engine?

Paul Lamar