As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
INTERNAL BAFFLE OF MUFFLER FOUND CRACKED AND PIECES MISSING. A LARGE ROUND PLUG PIECE WAS FOUND BLOCKING EXHAUST TAIL PIPE CAUSING LOSS OF POWER. DISCOVERED ON GROUND RUN UP PRIOR TO FLIGHT. PILOT RETURNED TO PARKING AND CONTACTED MAINTENENCE.