Compression tests are really meant to look at compression across cylinders, not compared to other motors. For example, I had a tired OEM starter when I ran a test just after a rebuild. The numbers were in the low 120's. Then the starter went out and I replaced it with a high torque unit. Being paranoid about my engine, I ran another compression test about 3000 miles later and found I had numbers in the high 130's, and consistent across all cylinders. Nothing but the starter had been changed. If you want to get an idea of the true state of the cylinder you have to perform a leak down test.
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