Had vrsf catless dp installed 1k miles ago with new o2 sensor, mechanic didn’t specify pre or post wish i knew ab. A bad oxygen sensor before catalyzer on bank 1 has caused me rough idle, misfiring codes and deteriorated the situation into limp mode The post catalytic converter o2 sensors are relatively easy to remove insitu
How often should the oxygen sensor be replaced? How about oxygen sensor
The bungs in the exhaust system need to be heated with a torch to expand them and break the rust bond.
Based on what you said were your tools you have available to you and not a lot of wrenching experience (my assumption), take the car to an independent bmw mechanic and have them.
