Compression Ratio

[SeaHawk]

I have a 1991 Pro50 outboard. The Yamaha manual states that my compression ratio is 6.

Do I take the number 6 and multiply 14.7 atmospheric pressure to get my actual compression reading?

In doing so, is 88.2PSI the reading I should be looking for when I do a compression test with all the spark plugs removed?

With all three spark plugs removed, I used a new PSI gauge and got readings of 90-95PSI in all three cylinders. Is this the compression rate I'm trying to achieve? I was told by a local mechanic who tested my motor that my compression reading was 115PSI in each cylinder.

[boats.net]

When testing compression remove all plugs and open throttle plates. Compression should be no more than 10 % difference between cylinders. There is not any specs on what compression should be just should be even.