[davepl]

Just FWIW, the diameter of the line has NOTHING to do with the pressure. Basic laws of hydraulics tell you the pressure is the same throughout the system at all points.

There could be flow issues, and it could be that rear discs (as a made up example) could need a larger line just for fluid flow, but the pressure is what the pressure is.

Put more simply, line size affects only flow rate, not pressure.