Pressure gauge on PMM coolant filter

[hogasm]

Has anyone added a pressure gauge to their coolant filter. The PMM set up does not have a port on the housing to add one.
Is it as easy as drilling and taping the housing or would it be easier to add it to the lines.

[Term3]

I also was thinking of drilling and tapping a spot in the filter head for a pressure gauge. Just trying to decide if I'll put it on the supply side or the outlet side, don't think it makes a whole lot of differance.