DOnt let people freak you out about the poly pipe inside the house. Most plumbers wont touch it because they have little experience with it and its a PITA. Instead of changing all of your plumbing out, I would just install a new PRV to insure it is working correctly then lower the psi to 50-60 and it will be fine. If you have the blue polybutylene pipe out side I would put the new PRV out by the meter and that would lower the PSI inside and out. But I do recommend that your get the blue (if you have it) replaced. If you do get the outside re done, call a reputable irrigation contractor, it blows my mind on how much plumbers charge just to replace one pipe. It's one trench, driveway bore if needed and one pipe. They sometimes charge more the we do for an entire irrigation system.