I got back to the garage and started pulling spark plugs out. I was excited to get some decent readings on the first couple cylinders and then on cylinder number three, I heard a loud POP! 'This can't be good' is all I could think. Luckily, or unluckily, the pop was the rubber hose on the compression tester. For whatever reason, it ruptured near the spark plug. I was able to get the reading before the pressure escaped. The upside is that cylinder 3 had good pressure, the downside is that I wasn't able to get cylinder 4. Guess I will be trying again in another 3 months.
Results:
Cylinder 1 (closest to fan): 155
Cylinder 2: 168
Cylinder 3: 170
Cylinder 4: ???