The general recomendation is that if your mainline pressure is above 80psi, then you should install a brass pressure regulator... yes, the same kind used for a house, not an "irrigation" regulator. The only thing I know of that are "irrigation" regulators (speaking as a DIY in irrigation) are the PVC regulators that I've been told are only supposed to be good down stream of the valve, in otherwords, for drip irrigation.