I wanted to clarify what each of these plugs are for:



From left to right -->

O2 Sensor
O2 Sensor
EGT Sensor?

Someone please confirm, thank you!

 

In theory, because the rexpeed downpipe only has one bung for the O2 sensor, if you wanted to run a wideband, you'd need 2 extra holes. Someone more knowledgable than me might have a better answer though.

Left to right
Wideband
O2 Sensor
Wideband

 

It's strange that Rexspeed didn't include a nut for the wideband hole. I'm not running one, so it would be nice to not having to run to the hardware store.