The z33's are bigger but not by much. they will need better spacing to not hit the wheels also. Most importantly, the real difference between the z32 compared to the z33 is the Bling factor and Fade at the track. Other than that it isn't much different. both are more brake than the car really needs unless you are gonna road race at the likes of Sebring and Moroso etc... If you are going to track it like that you should get better fade resistance from the z33's though. Also, you are looking at almost double for every brake change and thats if you do them yourself. \

You can get the z33's because some of the Z33/G35 owners are opting to go to the other brake set up rather than pay the price it takes to do the brembo's. Its actually cheaper to buy the regular z33 calipers from the base model and swap them for the Brembos rather than pay for a brake job with that set up......