Woow I was in the market for one of these some years ago when I had my RX7. Since those cars usually still have to go through emissions, most regular cats get destroyed in no time due to the rotary. These spun metalic cats work wonders. You might also want to try posting this on
Mazda RX7 | Owners, Parts, Repair, Performance, Mods, Wheels - RX7Club.com. Since it's 3" I'm sure you'll snag a buyer over there real quick.
GLWS!