Originally Posted by Z1Performance

If the car spends the majority of it's life off the track, I'd suggest the comfort unit. The only downside with the race version will be the increased chances of NVH due to how stiff it is. The comfort version will give most of the benefits that the race one does, but still keep things happy and quiet inside the cabin

Sent a test unit (comfort) to RCZ today for his independant evaluation

Since someone asked, diff mounts are no big deal to do - I just need to get my hands on a rear subframe to take the measurements (they are different from the 350Z, though not significantly). Look for those to come out in the coming months.