Ya need to start with larger diameter main line.
Run a main of 3/4 or 1". The longer the run, the larger the I.D.(bigger I.D. = more flow)
Tap off of that with the smaller diameters.
I run my system at 30 psi.
The longest run i have is about 100 feet of pipe.
90 degree elbows loose flow too(20-30 percent?)
Soft turns are your friend.
If ya add a booster pump, you might as well tap into the supply coming out of the wall. You can then have the whole house at 70-80 psi, and showers will take less time then. And a slight(10-20 bucks) increase in the electicity bill.
