Removing back seat area FD
 

Anyone here cut out the floor of the back seat area? Essentially everything between frame rails behind the front seats. Any pics? How much did it weigh?

https://cimg9.ibsrv.net/gimg/www.rx7...0c4f45f366.jpg

Isn't much you can cut out of the rear seat area that doesn't have a direct structural tie-in. Well, the FD is a unibody chassis after all.

XP RX-7s are ~2,000lbs without cutting on the unibody.

I believe later JGTC FDs and the Garage Revolution FD are tube front/tube rear with just the center unibody left also ~2,000lbs but with more structural rigidity and meeting safety requirements. For pics of that Beyond the Dyno: Garage Revolution's Time Attack FD3S RX-7, Part 1

What exactly are you trying to achieve and in what racing class?

If you cut unibody you will want to be replacing it with some kind of structure.

I believe 7Parts.com can sell you a 1:1 scale CF FD body if you want to put that on a stretched wheelbase go kart or whatever for maximum weight savings.

Sounds like you should mount the shocks for the rear axle to the cage as well as the rear axle locating bars (if you haven't already) and just cut the entire rear of the car off from the front of the rear wheel arch back.

Then get some FG rear over fenders (obviously the kind that cover from the door opening and wrap around the rear) and a FG rear bumber cover to make up the rear bodywork. That would save some real weight.

Not much weight in just the double thick sheet metal on the floor where the rear seats would be, but more weight up in the stock rear shock mounting area where sheet metal is built up as a truss to go up over the rear wheel arch and back down to finish the perimeter "frame" to mount the rear of the stock subframe and give some structure where the open hatch area is above.