Hello Lou,
If you use larger pistons then there is a larger area for the hydraulic fluid to fill in order to push the piston out,so therefore useing calipers with larger piston diameter will decrease the pressure at the front calipers.
After saying this if you have an adjustable in line brake bias control then you can simply dial it in to how you like it : ie decrease pressure to the rear brakes, this will effect pedal feel.
Good luck with it
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Cruising in 5th
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