Ha...yes, I get it. Hopefully it will remain sealed tight then. If not anyway, the symptoms are quickly noticeable from the irregular idle. I'll keep an attentive ear on it...

 

M. Stojanovic, you were spot on again...

The sealant quickly became brittle and I had to unplug the sensor to avoid having the crazy gas consumption.

When trying to tighten the nuts a bit, the first stud snapped instantly.

I just received the OEM studs, nuts and gasket that I finally ordered, and will pull the cat again today.

Just to be on the safe side, is it required to put some copper or graphite grease on the gasket, or not really necessary?

 

I didn't use anything on the manifold gaskets, just wire-brushed the flange surfaces. I suggest you do the same because, more or less, any compund you put there will burn and may then create micro passages for the exhaust gases.

 

That makes sense indeed. Ok then, I'll do as per your advice, and hopefully, this will be my last message on this thread

Cheers !