Try removing your shower heads and test the pressure without the head installed to eliminate the head as a source of trouble. If you have great pressure without the head installed then you likely just need to clean the shower head you have (or replace it) rather than repipe your home saving you thousands of dollars.
I can’t tell you the amount of times that an unsuspecting homeowner was told by a plumber that they needed a new piping system when all I saw were dirty screens at the fixtures!
However, if removing the shower head does not provide water pressure, we are happy to help. Just call us at 818-625-7772 in the Los Angeles area.