[Dawko]

I ordered a new rear muffler for a 320i Touring from Eisenmann. When receiving the VIN I checked the specs and this shows it has a B48C (B48B20A) engine. Quick search resulted in a different exhaust than the B48B previously found in the 320i, the diameter is reduced.
So now the options are welding to the original midpipe or using a pipe reducer of some sort. Not a fan of both options.
I was already toying with the idea of getting the race midpipe as well but this deletes the OPF thus probably giving a CEL?
The midpipe should connect without fitment issues as the car uses the same DP as the 330i B48B.

Now can I run the midpipe with the CEL without causing too many issues? Will the ECU intervene in some way to correct anything?

I know a tune would eliminate this but considering it's a lease I'm a bit wary going this route. Best option would be JB4?