OP: I'm a little lost reading your post... but I'll chime in based on what I see..
There are a bunch of different ways to deal with the rear o2 sensors. They can be turned off which leaves catalyst monitoring in an unready state, or changes can be made to leave these monitors in a pending state. The other way of doing it would be to remove faults associated with them, which would leave them functioning but not throwing a SES light on the dash.
Now, I do have a few clients that have NO post cat o2 sensors at all. And as pbonsalb said, even with the rear o2's turned off, the car is still looking for the heater circuit and will throw an additional fault if the sensors are unplugged.
If you look closely here: http://www.m3post.com/forums/showthr...t=dinan+teaser
- you'll see that the OP does not have any post cat o2 sensors installed at all.
When I tuned his car, he told me that he had no plans of putting in the post cat o2 sensors, so I modified the code properly in his car to ignore the rear o2's as well as the heater circuit it's looking for. You can certainly use your own wideband sensor there where the stock post cat o2 sensors are - without errors - that way you won't need to weld in an additional bung. You'll just need a calibration that is set up in that regard, very easy to do.
The best thing to do is to see what faults the car is throwing, and if it is infact the heater circuit for the rear o2 sensors, either replace them or have a competent tuner modify the file to ignore monitoring of that circuit.
I hope this helps.