This was discussed recently on the mailing list, but I don't think there was ever a definate answer to this...What is the size of the bung for the rear 02 sensor (size/thread pitch)? Where can I purchase a piece like this? I'm going to be making a 3" test pipe and need to get the rear 02 sensor mounted in there somehow. If anyone has that info, please post. Thanks.

The rear O2 sensor threads are 12mm x 1.25.

You can use a nut from an auto parts store and weld it onto the pipe. I make 2.5" and 3" test pipes for SR20's if you don't feel like making your own. They feature all stainless steel hardware, 1/2" thick laser cut flanges, rear O2 sensor bung for OBDII cars, and they are fully ceramic coated. All welds are high quality TIG welds like what is seen on F-MAX products. I sell the test pipes for $110 plus shipping.

Let me know if I can help.

Later,