[thetyrant]

Ideally before the cat but as long as your aware of the difference a Cat makes to the AFR numbers (google it if not) then its ok after the cat and tune accordingly, i know many tune with a tailpipe clamped wideband (so well after the cat) and while not ideal it can be done effectively if you fully aware of how thing are affected doing so, a lot depends how close to the limits you want to get as well, closer you get to the limits the more accurate the data you need to be safe, so before cat AFR and EGT monitoring etc is best but for milder tuning not essential.

 

[thetyrant]

There is a display interface which was made by Innovate, I think it is called the OT2 or similar.

It plugs into the OBD port to allow the display of engine sensors on laptop/ipad/iphone and it also works as the interface for the wideband sensor allowing you to display real-time lambda sensor readings.

It can do many things including work as a "rolling road dyno" on the move for working out power curves etc.

It is quite accurate when the correct data is put in.

My r53 & previous e36 were both within 1hp of wheel HP when I did my runs a few years ago, which is when it was last used (Just using OBD data not O2 sensor data as I never got to fit it.

I hadn't noticed Innovate did these now quite handy by sounds of it, so if ive got this right you have the Wideband controller/Sensor like LC2 etc which is MTS compatible which then plugs into the OT2 interface, which in turn is connected to the cars OBD socket so you can then datalog the OBD info from car and add in the Wideband AFR info ? I could be interested in it if the OP isnt as my wideband setup is pretty old and logging is always a hassle with different software and hookups etc.