Do I need a new tune to do this, or is it something I can do through the parameters. I didn't see a setting to do so.

I am cutting out my cats and welding in straight pipes, so no bungs here.

 

You would have to get a custom tune to do that. You will get a check engine code without turning off/deleting the rear 02's.

 

Thank you. What if I just installed an o/r h and reinstalled my rear O2's, would I still get a CEL?? Also I have a problem with my X3. Sometimes it boots up and other times get just a blue screen, any ideas??

Thank you, nobody has been able to give me an answer.

 

Yes you would still get the CEL in that case, because if they are installed but not turned off, the computer will see that as your catalytic convertor is not functioning properly.