difference between o2 sensor in x-pipe vs in cat.
 

What is the difference between the two sensors, and how does running without the cat and the corresponding sensor affect the engine?

Or is the sensor in the cat a temperature sensor?
Is this a not a common sensor on US cars? My car is a Japanese import.
I would like to know if I can remove it when going to a high flow cat, or whether I need to have a bung welded to the new cat.

my acura had 2 sensors. one precat is wideband for the ECU to control AF. one postcat is narrowband to test emissions. guessing same kind of setup on the 951.

if u remove the second, it'll prob throw a code thinking the cat isn't working...which it isn't.

I'm certain that none of them is a wideband as the DME can't handle wideband signals.

The x-pipe o2 sensor is a 3-wire heated sensor while the one in the cat is a single wire sensor.
Anyone?

The sensor in the Cat is a temp sensor on the Jap Market cars only (Part # 951 606 019 00). No longer available from Porsche. This sensor is not linked to the DME as far as I know and only controls the "EX" light on the dash. If you are removing the cat then grounding that sensor wire should stop the blinking "EX" light on the dash

Ta mate.
That clears things up and explains why nobody new about this sensor.

Btw.
I lived in Te Kauwhata for a year. You've got some amazing roads down there. Would have loved to have had my car back then, or maybe even a Subaru WRX...

Yeah they are sweet roads. Funny you mention that because the last time I was out there in my S2 I had a WRX duelling with me. Mechanically I don't mind WRxs it's just the spotty, caps on backwards, sagging pants teenagers that are drawn to them that bothers me....
(let the flaming begin...lol)