As the title says i have the caliper brackets for the larger RZ brake discs but cant find where to buy them from. I came accross a site on the net.
Triple-R: 1999 Mazda RS/RZ Rear Brakes Install

It say a company called PRECISION BRAKES, but ive emailed them and no reply.
Does anyone know where i can buy a set of the larger RZ rear floating discs?

 

This is my solution.
Big Brake Kit (OE Caliper) - RX7 REAR 93-95

 

Precision brakes isn't around anymore. I understand their customer service sucked. Can the dealer get them?

I have read of some people taking measurements and getting Coleman Rotors to build them to spec. They may even have the specs on file...

 

If you are in the UK find a dealership that sells dixcel brake products. They have all kind of discs (slottet, drilled, plain) that fir the RZ/RS/Spirit R models. The prices are really good! I payed 650€ for all 4 discs.
They were recommended to me when I lived in Japan as a good alternative for the OEM products.