Air Arms Owners Club

Hi guys
Advise please I am setting my lads s200 up and I am wanting to know what is the best pressure to set the gun at...
As I have no gauge or regulator fitted

Is it worth fitting a regulator and gauge and if so which make..

I fill my unreg'd S200 to 170bar
Huma external plus quickfill and gauge on my other one,
I think the quickfill and gauge are from Robert Lane
I think it's a good upgrade