Dear me ymetimme. I understand many consider plumbing a gauge at the wand head as butchering a wand much like putting a hole in the side of your vacuum tank to place a gauge there. The point on putting a gauge at the wand head is that is the location of the cleaning action and so some are interested in the actual cleaning powere at that location. That is where you will see the real vacuum performance. I would venture to say if you put your gauge on the inlet of the unit your water lift would be the same as what you already measured. That is not telling you the performance of your vacuums at the carpet. If you are only interested in lift at the machine you did a superb job. Keep up the good work.