The Inspector wrote:
Nice work! Did they find and replace the misfiring sparkplug that kept going 'bloop' 'bloop'?
A Merlin can sound different at idle depending on-
Spark Plugs- Original British Type, Champion Aircraft Type or Champion Auto Racing each is a little different.
Magnetos- BTH, Rotax or General Motors Northeast. Each sounds a little different and even point gap will change things a hair.
Cams- -7, -9 and Transports each have a different profile and will idle differently.
Carbs- There is an idle bleed air circuit difference between the carb for a -7 and -9. It affects idle cross over in some ranges and sounds different at times because of it. Then their is idle mixture.
I listened to it and I didn't hear anything that would cause me alarm.
As for important issues, thats why a pilot does a runup, so hopefully he will find and recognize any issues.