[OGpiney]

I bought a lc1 kit and have a 1" bung and a much smaller one already on my car which i was using with the aem kit. whats the tuning difference between both bungs ?

[cgrey8]

The thicker bung pulls the tip of the sensor out of the flow. That helps with the longevity of the sensor. I bought my LC1 before they started shipping with that thicker bung. And I use drilled-out spark plug anti-foulers to pull the sensor out of the exhaust flow. Here are the details on that option:
Here's some info from Cougar5.0 that came from a different WB thread:

I made a spacer for the sensor using a spark plug anti-fouler sold in the "Help!" section of most auto parts stores.

I used the Help! P/N 42002 18mm tapered seat non-fouler (due to it's longer length compared to the 42009) which I modified so the sensor would fit into it. I counterbored the large diameter using a 5/8" bit so the large diameter of the sensor would not bottom out. I added about 0.075" depth - from ~0.75" deep to 0.825" deep - DO NOT bore any deeper or you'll get into the diameter of the 18mm male threads and have 2 pieces on your hands. I then drilled out the smaller diameter to 1/2" so the sniffer "nose" of the sensor would fit. I beveled the 1/2" hole using the 5/8" bit so the gasses would tumble a bit as they pass over the edge of the opening & hopefully this will minimize any venturi effect. I then used the gaskets from a Help! 42009 spark plug non-fouler kit on both sides as the tapered seat of the 42002 would not seal well against the exhaust bung and the sensor seals better (and has to go less deep into the female threaded end) when using a gasket.

You can see the gaskets on either side of the spacer (pic in previous post above). I've run the new sensor for a bit and it seems to be working fine. I was a bit concerned about speed since the sensor is not directly in the exhaust flow, but the reaction time seems to be as fast as it ever was based on datalogs I've taken so far. With the sensor out of the direct airflow and the spacer acting like a heatsink/thermal mass, I expect that the sensor will likely live a long and happy existance. Total cost of the spacer - $9 (1 - 42002 $4, 1 - 42009 - $5).

The thicker bung is a cleaner, simpler option if you don't already have a bung welded in. Although if you have a standard bung welded in already, the anti-fouler is what I'd recommend.

[OGpiney]

ok I will install the 1" bung then. Thanks for the info.