So I got around to installing the seat rail bars that I got from Ryzan. So the theory with this kind of brace is to reduce the chassis flex due to the targa's. Installation was very straight forward and didn't take much time at all. Since my car is J-Spec, a little fiddling was involved. All there was to it was to remove the door sill and the rear seat interior trim to lift up the carpet. Once the carpet was lifted up, you could see a black sticker covering a hole where the ADM seatbelts attached to. All that was needed then was to make a hole through the carpet and bolt in the brace. So here are my thoughts after installation - Definitely noticed less noise when entering and exiting driveways where chassis flex usually occurs - The handling aspect of the car changed and it feels more predictable The only drawbacks I found where on the driver side, when you use the electric controls to push the seat back, the actual seat hits on the seat rail bar. Here in this picture you can see where the seat strikes the bar Just thought I would share this information for those thinking about something similar, as there seems to be very little write ups on this topic.
Apparently they work on 2+2 and 2+0. Someone on the Aus300zx facebook page had trouble fitting them to his 2+0 but fitted on his 2+2. I wouldn't be able to confirm fitment though....
