I had the same issue, to a lesser essent, in a car of mine. Turned out the MC just didn't have enough stroke for the pedalratio in the car. It just felt like the pedal itself was bottomout on something, while you know there should be some more stroke in it. Swapped in a random MC and the problem pretty much went away. Only need to fine tune the MC's piston diameter for best brake-performance now.
