[Fii]

My current setup has AEM on stock twins and a custom downpipe without cats and with a bung for stock rear o2 sensor.

I have the AEM gauge type wideband kit, which I am going to install this week. I have searched the forums, but could not find an exact answer to my questions.

I am going to put the gauge in stock clock location. Which would be the best place to mount the sensor? So far I see three options:
1) Use the front stock sensor location
3) Use the rear stock sensor location
2) Weld another bung to my downpipe and leave the stock sensors as it is

I have also read that the best way is to connect the 12V and ground wires directly to battery, but I don't want to extend and route some more wires through the firewall if it is not absolutely necessary. Is there a good source of switched 12V and ground behind the dash?

 

[SoarerTT]

i would go with #2...weld another bung to your downpipe and leave the stock sensor as is.

 

[Digital Tripod]

2

 

[Overclocker]

I’m going to use the AEM w/b gauge kit too and both replies have said to weld a new bung on.

I have a RMM style downpipe with 2 bungs already on it, one towards each end of the pipe. The end closest to the turbos has what I think is the stock O2 sensor in it. Now on the far end of the down pipe is an empty bung.

I would guess the AEM w/b sensor would go there, but the AEM install manual says “if you anticipate high EGT’s (over 800C), run a turbocharger… then you must mount the sensor at least 36 inches or more downstream of the exhaust port.”

Is it safe to screw the sensor in the existing bung in the downpipe or should a new one be mounted further down as in this MKIV.com article's photo?

 

[BLKMGK]

Where's got it welded isn't bad - you can also go several inches closer to the turbos to keep it out of the way of road debris. YES, wire it to the damned battery via a relay. If you do not do this you run the risk of having problems keeping the AEM and the gauge synched.

 

[Fii]

I have found a good spot to weld a bung about five inches closer to the turbos than it can be seen in the picture and on the top of the downpipe, not on the side. I will post a pic, when I it will bo done.