I have a 2g, im going with a 3" turbo back exhaust thats straight pipe untill the muffler, im having them put the o2 bungs incorporated. but how should i do the setup, ive been told many things and many of the same things but opposite sometimes. last i hear was go with an o2 simulator for the front sensor and a wideband for the back. any help on what to buy and how to do this? message me or email me at pipedreams96@hotmail.com with any kind of help. thanks alot.
Pat K
Oh and if it helps its a 1997 Gst. its in the process of getting the build together doing exhaust then all that nonsense before i worry about upgradding all the other stuff. if any one could help 
it scares me that you’re this deep into the project and don’t understand what each sensor’s need is.
I thought the front 02 was what the ECU used and the back was for emissions (that’s they way it is on the evo).
this all changes if you tell me you’re running a standalone and using the wideband as the main sensor for that.
Your front (Primary) o2 is used for the ecu to adjust the amount of fuel the car gets. Meaning, it’s the important one. If you were to run just a wideband, this would be the sensor to replace (and odds are you’d need a resistor in the original primary heater circuit to keep your car happy and free from CELs)
The rear sensor (secondary) o2 is ONLY FOR EMISSIONS purposes. It basically is looking for “clean” air. Meaning, your exhaust gases should have passed through a catalyst to clean it up before it hits the sensor. This would be the o2 sensor in which you may choose to run an o2 sim in the absence of a catalyst. (once again, to keep your car CEL free).
If you can’t clearly understand everything I just said, quit modding your car.