im making a custom downpipe and i need to know what to use as the o2 bung?

 

18*1.5 nut or you can use a weld in bung that k&N sells even comes with a plug

 

what size nut?

 

18mm x 1.5 pitch

 

You can get the bung and block off bolt from atpturbo.com.

 

You can also get them from a parts store like napa, advanced, pep boys etc.. I just got 2 bungs for 9 and change. looks better than a nut, round on the outside.

 

I'm suprised no one has posted this yet:

At the auto parts store in the section with all the packages labeled HELP there are things called spark plug defoulers. They are the right size for o2 sensors and can be cut in half and welded in. They work great and they are super cheap.

 

I coulden't find those anywhere. I went to about 5 HELP displays. no luck. Good tip if you can find them.