I just posted something on this today in the track-autocross-drift-dragstrip section.
My stock clutch started slipping at around 15k at anything at 6500 rpms and above. That was with a lot of different drivers, track and autox days. Then I boiled my clutch fluid this summer, but thought the CSC failed, and decided to replace everything.
If your looking for a replacement, this is I went this direction, and I'm really happy with it. I'm still on the fence if I should have gone with the aluminum flywheel or if the light weight steel one that I got is better.
South Bend complete clutch package stage 3 daily and the ZSpeed HD Concentric Replacement CSC
2009-2011 370z clutch kits