As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN)EXHAUST CONE BROKE OFF INSIDE THE MUFFLER ASSEMBLY CAUSING A PARTIAL OBSTRUCTION TO THE EXHAUST PATHS OF #2 & #4 CYLINDERS. BECAUSE THE ENGINE CONTINUED TO RUN SMOOTH THE ONLY INDICATION OF A PROBLEM WAS A SHORTFALL OF THE FULL STATIC R.P.M. THE NEWER MUFFLERS HAVE A CONTINUOUS PIPE THROUGH THE RESONATOR, UNLIKE THIS FAILED ITEM WHICH IS ORIGINAL PIPER EQUIPMENT AND IS JOINED INTERNALLY WHICH CAN LEAD TO COLLAPSE.