I doubt that many of us have mains pressure as high as 80PSI, but if you did what then?
As long as your system holds up under the pressure I don't think it matters. I ran mine for years with the pump in front of the prefilters with no issues. Then I bought a new RO and the prefilters on the new one wouldn't hold under the pressure of the booster pump without doing then up ridiculously tight . Only then did I reposition it behind the prefilters.