Hi Chris,
I changed to 0625 front and 075 rear and I really expeceted this to work but no, (I genuinely could not lock the brakes at 20 mph on a wet road).Its like the rear brake is stopping the front cylinder working because the pedal is so stiff, so hours later I changed the rear to .7 and finally the front brakes are now working but I have a long pedal travel So I then changed the front again to .7 (Now back and front) and no not happy with this, so best combination so far but not happy is .7 rear and .625 front.
I am now thinking of changing the calipers to ones with a smaller piston size. or am I really missing something here ?