Do you have an adjustable pressure regulator. The standard ones are set at 40lbs, we picked up one at FMCA and set it for 50lbs. I was told I could go higher, but this was enough to increase shower pressure. Just recently the hot water pressure in the show started dropping significantly. It appears the shower valve failed/slipped/whatever. I noted in a previous post today that Moen sent a new valve, and replacement was fairly simple...even for me.