The first priority is to obtain actual performance data, particularly with reference to turbocharger behavior. The full story would require a dynamometer to extract, but one can gain useful insight by observing the changes in manifold pressure under working loads that, at some point in the test, should be great enough to cause the wastegate to open. The rise in oil temperature and variations in crankcase pressure supply additional parts of the picture.
Do not operate a turbocharged engine unless the air cleaner (or spark arrestor) is in place and the intake-side ducting secure. The compressor acts as a vacuum cleaner, drawing in foreign, objects which will severely damage the unit and might cause it to explode. The troubleshooting chart makes reference to coast-down speed. If you feel it is necessary to observe compressor rotation, cover the turbocharger inlet with a screen to at least keep fingers and other large objects out of the mechanism.
When dismantling a turbocharger and related hardware, make a careful tally of all fasteners, lockwashers, and small parts removed. Be absolutely certain that all are accounted for before starting the engine. Immediately shut down the engine if the turbocharger makes unusual noise or vibrates.
Turbocharging (and supercharging generally) put severe stress on lubrication, air inlet, crankcase ventilation, and exhaust systems.