As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AC HAD 180 HP ENGINE INSTALLED ON 7/10/96. AC HAS 1443.5 HOURS SINCE INSTALLATION. OPERATOR NOTED 2300 RPM AT CRUISE, FULL THROTTLE. INSPECTED AND FOUND AIRBOX STILL HAD THE HOLE SIZE FOR 160 HP ENGINE. AIRBOX HAD NOT BEEN MODIFIED IAW STC. IT HAD BEEN REPAIRED ON SEVERAL OCCASIONS SINCE ENGINE INSTALLED AND HAD NOT BEEN FOUND. (K)