z1 rear diff kit
 

has anyone installed it? any idea how much work it is? is it worth the money?

are you talking about the bushings? I had them installed it took about 4-6 hours. It is definitely worth the money because the fluid filled ones are prone to going bad.

Yea, bushings, fluid and diff cover, description says that you get smoother shifts (i have 6mt) did you notice a difference? i only have 20K on my 09...but smoother shifts would be nice.

I have the 7AT. I only did the bushings since one of them went bad. I had a little wheelhop between shifts if I was accelerating with any force. Once I found out it went bad I drove like a grandma for a few weeks lol but now it feels a lot better. I can't really feel a difference from when I got the car but I feel a lot more confident now in driving it hard