Thanks so much guys for your inputs it really makes sense.
I know when I first installed the booster pump in had the flow switch on it. It worked great, you could take a shower with real nice pressure. Then the flow switch went and I installed the pressure switch and it was never the same. So at the point with several things running I don't believe flow was a problem. Nothing ever cavitated. As for the filters they installed I have just changed them on a regular basis. I will check psi settings.
How come with the technology age we live in they don't have digital pressure switches.
Also : If you changed the flow switch, and it isn't working anymore, chances are, it needs whatever switch was on there, rather than the pressure switch you replaced it with. What kind of pump is it?