Anyone happen to know what thread size nut you need for the stock catalytic converter on a S4 turbo to connect it to the rest of the exhaust?

 

Isn't there a bolt that attaches to the other side? Take that bolt to the store and find the right size...

But... it might be M12 x 1.25. Try that if you can't do the above. Bolts are like $.10

 

ahh, that raises a curious question that I had. When I first removed the catalytic converter, as part of the process of disassembling the entire exhaust, the nuts and bolts were rather rusty and stuck. One nut I removed while the other nut was totally rusted onto the bolt and I removed both nut and bolt as one piece. This surprised me, so I removed the nut, and jammed the bolt back in where it came from. Question is...how is it supposed to be constructed? 'Cause the bolt didn't seem to be attached to anything on the other end. But then again it did seem to come out as a single bolt rather than me pulling out a whole chunk of the catalytic converter.

 

It's a 12 x 1.25 mm stud. Mazdatrix has them on their website, if you want to buy or see a picture ( http://www.mazdatrix.com/e7.htm ). One of mine would just spin if I tried to take the nut off, so I would have to use vice grips to hold the stud while removing the nut. Then, when putting the nut back on, it would always tighten up as much as I wanted with no problem. Weird.

 

Mazdatrix wants $6.15 for that.