[Hethj7]

I would think a simple air pressure gauge would work fine for this. They work by measuring a pressure difference (i.e. the pressure difference of the outside atmosphere compared to the charged air inside).

One concern I would have is what kind of pressure increase you are expecting to see with a smop pump. I wouldn't think a smog pump would provide enough pressure to really help out anything, but I am not sure. Maybe someone else can chime in on this issue.....