As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE AT 4000' THE PILOT EXPERIENCED A PARTIAL DROP IN MP ON THE RIGHT ENGINE. A DIVERSION TO KPBI WAS PERFORMED AND THE AIRCRAFT LANDED WITHOUT FURTHER INDECENT. A POST FLIGHT VISUAL INSPECTION REVEALED THAT THE LEFT REAR EXHAUST PIPE HAD SEPARATED FROM THE FLANGE ON THE TURBO Y PIPE. THE REAR EXHAUST PIPE AND THE LEFT INTERMEDIATE EXHAUST PIPE THEN EXITED THE ENGINE COMPARTMENT THROUGH THE COWL FLAP OPENING AT THE BOTTOM REAR OF THE ENGINE NACELLE.