I think mine could be caput, although could be some air in the ABS (not the lines as they've been bled twice, once by dealer and once by me). Brake pedal feels good when I get in the car and start and press it for a while.

After driving down the street though, feels like the clutch pedal for 90% of the travel, then the last 10% it comes in like vice grips and tires are locking. By this time I'm standing on the brakes though.

If I do need to replace it, I'm trying to figure out if the GT2/TT/GT3 part is the same as the C4/C4S part by TRW who makes the Genuine Part. The part numbers are

C4/C4S 996 355 910 40

C4/C4S TT GT2/3 996 355 910 50