If you think using a liquid gauge is not beneficial, just try using a gauge without liquid and let us know what you find. From my understanding the gauge will break, but that's not what this thread is about. There's a guy who has been very helpful that has very good YouTube videos on pop testing and cleaning injectors for the OM617. He told me that my pressure seems to continue to rise even after I've stopped pumping, and he thinks it's a result of going from 1/4" fittings up to 3/8" fittings. I ordered the right fittings and will hopefully have an update tomorrow.

The gauge does seem to be delayed because from what I can see the injectors begin chattering at 400 PSI. Hopefully this is due to the fitting sizes and not a faulty gauge.