Hydrant Pressure Reducer?

This will be my first attempt to use this source to solve a problem. Please don't let it fail me.

I'm evaluating 2.5" handlines and smooth bore nozzles. A problem I have here that is unique to us is our high hydrant pressure, 150 psi plus. All of our lines are as stiff as boards due to the pressure. Gating it down works great as long as the nozzle is open but once it is closed the pressure quickly builds to 150 psi. This has always made our 1.75" tough to move and as you can imagine the 2.5" is a beast. The whole Idea is to gain GPM and make the hose easier to move.

My question is, do any of you know of any way/thing to drop the pressure? I'm wide open to ideas.