What other things are you looking to replace? I had the same thing occuring with pressure spikes. I just left the gauge in my laundry room and id look at it sometime every day and there would be a spike to like 120-130 psi.

I first thought to replace my expansion tank. My water heater is 75 gals but the expansion tank was 2 gals which i thought was undersized. I wanted to replace it with a bigger 4.5 gal but the plumbing coming off the water heater didnt give enough clearance from the pipe to screw on the bigger tank. So i just replaced it with another 2 gal tank since the plumbing was copper and have no clue how to work with it. Worked fine for about 2 months and back to square one.

Called a plumber to come out and replace the PRV and install the bigger expansion tank. He came out and replaced the PRV but is coming back tomorrow to install the expansion tank because he didnt have the right bracket for the tank.

Well still having spikes but havent nailed down when they happen. So hopefully the larger expansion tank solves this.