If you'd got the space to spare and can get a OS Giken close ratio setup at discount I'd keep it for a while. Most people I know have just replaced the older '03-'04 (and the CD008 from early 2005 models) transmissions with the CD009. But if I ever had to upgrade/replace mine I'd go the OS Giken route, I really like those gear ratios. Pair that transmission with a nice final drive and you could make a great responding NA 350Z. I'm such a parts purist that if I did that I'd feel the need to ditch my Exedy clutch and get one from OS Giken, as well as new limited slip since I'd invariably want that to match too.
Wow...I just made that a really expensive upgrade to my Z.
