Adjustable Pressure Regulator

It can be taped onto the male threads of the outputs of many timers, while the fitting you had on the tap, simply screws onto the male threaded output of the PRV. It's that simple!   

If you find that your water pressure varies a lot, then a pressure reducing valve can be useful to reduce the high pressure peaks.

This will help your irrigation system as LeakyPipe prefers to work under more even water pressure. The steadiness of the pressure for a LeakyPipe system is more important than the exact pressure.