FYI
They all wear out fast if they aren't installed properly. When you take your old struts out there will probably be oil in the strut tubes - this is not from the struts being old and leaking. The oil is there to transfer heat from the strut to the strut tube, you can overheat your struts and it kills the seals. So make sure when installing new struts to fill the space left over in the tube with standard motor oil, fill it up till the oil is about 2" from the top of the strut cartridge- not the tube.
My KYBs wore out pretty quick, not completely blown but a major degrade in function within 1.5 years and the front passenger completely blew. I only lowered my Z about 1.5" I've had much better service from the tokicos but I prefer bilstein and Koni (if you can find new ones).
Matt