As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING MAJOR OVERHAUL WHILE INSTALLING MUFFLERS WITH NEW SUPERIOR 'BLO PROOF' EXHAUST GASKETS, FOUND GASKET TO TOUCH INTAKE ON ADJACENT CYLINDERS 1 AND 3 AND WOULD NOT FIT FLUSH AT CYLINDERS 2 AND 4. THIS COULD LEAD TO EXHAUST BEING DIRECTLY PORTED ON INTAKE GASKETS AND BURING THEM OUT CAUSING A LEAN CYLINDER CONDITION. PROFILE GASKET EDGE.