Factory Exhaust Bungs

[Grinder34]

Does the OEM header/up combo have both an O2 and an EGT?

I have an aftermarket header/up combo with THREE bungs, and I'm trying to figure out the third. So far i've got front O2, and bung for aftermarket EGT, but I cant figure out the third. I want to know if i need a plug for it before i try to do the install. I'ts right near the turbo by the O2 bung.

 

[Grinder34]

Older Wrx have EGT. Newer Wrx and STi do not have EGT on the harness from the factory. The third bung may be for a wideband before the turbo. What size is it? If its neither EGT or O2 size, the bung may be for a backpressure sensor.

Looks to be the same size as the EGT close to the head, which is...1/8" npt? Much smaller than the O2 anyways. I'll have to get a plug for it then.

 

[Grinder34]

Do you happen to know the size of the egt? I just tried to google with mixed results. I cant tell if its 1/8 NPT, 1/4 NPT or M12x1.25