When screwing the 02 sensors into out cats I forgot which one goes where. The grey one vs the black one? I think the shorter grey one goes into the end closest to the hot side turbo right?

 

Opposite...black is closest to cat inlet and the grey is farther away.

 

Hmm well that would explain my 02 sensor errors then. I dunno why but for some reason I've got the grey one plugged into the CAT inlet (turbo hot side) and the black one on the side closest to the bumper. Boo...

Cheers!

 

do you use any gasket glue or teflon tape or just screw the o2 sensors in?

 

screw 'em in and tighten them with a wrench...