I rebuilt my C36GET engine last year. Book compression ration is 8.2:1. Measured wet pressures on all 6 were 12 bar (176 psi) +/- perhaps 0.5 bar.
So my take is that all these figures are on the low side for a 10:1 compression ratio - but I don't know anything about the X20XE engine, and I have no calibration data for my pressure gauge, and you have no calibration for yours So lots of unknowns.
The fact that in your results they're all very close says there isn't anything dramatically wrong with any particular cylinder. Doubt it's valve related. It could be overfueling, but you'd expect the lambda sensors to be complaining big time if it were that. How many miles on the engine? If it's a high miler could also be worn rings and/or bores.
[/quote] its done 149,634 miles,
sorry dont know how this quote thing works lol