I've done some searching, but I haven't seen this answered yet. I just got a third-hand highflow cat and put it on my eg hatch along with a greddy sp2 this morning. It seems the cat has an obd2 sensor plug, which obviously my eg has no need for. I don't want to ruin the threading by just shoving something in there -- what would you guys recommend sticking in there to seal off this very LOUD "leak"?

 

spark plug with some thread sealant

 

Seriously? wouldn't the electrode disrupt the air flow? Even if it did, I might do it just to say I did it