As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED DURING FLIGHT, HE COULD SMELL EXHAUST AND ENGINE NOISE WITH CABIN HEAT ON. HE ALSO FELT BAD AFTER THE FLIGHT FROM ST. LOUIS TO KANSAS CITY. THE HEAT MUFFLER WAS FOUND TO HAVE A ONE INCH HOLE IN IT AND SIGNS OF EXTREME DETERIORATION.