[PeterWT]

As I understand it, the function of the exhaust flap is to decrease the time it takes to heat up the cat on cold start and provide some minor sound modification, depending on the drive mode & RPM.
Well, I don't care for, or want any of that, so I've considered doing this since I got the car. I finally got around to it.
I ordered and installed the BMW M Performance Exhaust Flap (Dummy) Actuator Plug Cover. That is the part that comes with the M Performance muffler, which doesn't have a valve. So, when installed it tricks the ECU into thinking the valve is still there and no error code is stored.
I tie-wrapped the wire/plug out of the way and covered the female socket on the valve with electrical tape.
It's an easy job and eliminates the valve, without an error code. It's not a big difference in sound, but I'm glad I did it.
The combination of resonator delete, OE muffler and open valve sounds great and it's the best bang for the buck!

Call me old fashioned, but if I have 2 tail pipes, I want the exhaust to always flow out of both of them.