My city supply pressure varies from 50-60psi, depending on demand in my area of town.
My folks' well pump was set for 40psi, which made the low-flow showerhead flow a bit too low.
If your shower is dribbling, perhaps you have scale buildup within the supply pipe. Flow test it by taking the head completely off, and seeing how long it takes to flow a couple of gallons (Use a bucket). If you are under 2.5gpm with no head on the pipe, you have a restriction somewhere (assuming pressure is good).
You can get a pressure gauge that screws to your outside faucet in the sprinkler system area of Lowe's/Home Depot.
Pressures vary widely. Pressure reducing valves are typically required when the pressure exceeds 80 psi. There are parts of my city where pressure can go as high as 120 or so psi. Other parts of the city it could go down to 30 psi or less....where a kid's toy octopus needs half it's tenacles cut off in order for it to work properly.
Don't forget that showerheads have flow restrictors built into them. Any house built in the last 20 years will have them. They can cause the pressure to seem less than what it should be.
I don't mean to turn this into yet another thread on showerheads as there are plenty of good ones on this forum. Do a search and you'll find plenty of good information about low-flow showerheads and how to modify them.