I was trying to get an inactive drip zone working in this house I just bought, and it appears to me that there is no pressure regulator (or filter for that matter) downstream of the automatic valve. The pressure seems high and it's blowing emitters off the tubing. Would it be ok to just cut into the plastic pipe over by the plants, and splice in an inline pressure regulator with compression fittings? If this is a really bad idea I will cut out the old valve and replace it with a new valve, filter, and pressure regulator.