I recently purchased a new CAT.
I dropped my old cat out disconnected the O2 sensors, then continued to put the new CAT in.
I raised it into the bottom of the car, but the rear O2 sensor hit the bottom part of the transmission. I later found out that the CAT I bought was for a manual tranmission.
Can anyone point me in the direction of a CAT meant for a automatic transmission 05 Rx8.
Thanks in advance.

 

MAZMART - Serving The Mazda Community Since 1980. RX8 Catalytic Converter

 

If it's a magnaflow just relocate the hole farther back, drill a hole and find a nut at the hardware store that the O2 sensor will thread into and have it welded in place. Any good muffler shop should be able to do this rather quickly.
FYI if it is magnaflow keep a good eye on it mine lasted just over 10k with new engine and ignition system.
Now hollow stinky but no CEL.
Good luck