Found this read very helpful over on my350 when I upgraded my clutch master cylinder. Followed the directions and install was straight forward.
So long story short I have an exedy twin plate clutch and was suffering the dreaded sticking pedal. Replaced the OEM master cylinder and literally 2-3 weeks later it failed as well. Bought the wilwood and replaced the OEM rubber mastercylinder/transmission interface with a steel braided line. 7000 miles later and not once has the sticky pedal happened.
(even in socal traffic at 4:30pm)

Here's the link: http://my350z.com/forum/engine-drive...-cylinder.html

Seems to be a well know upgrade in the z community.