Just did this mod today and can't believe I didn't do it for 3 years. I did it only because my car went out of warranty.
Anyhow, it was not as EASY as everyone says to do because of the bleeding part. The bleeding hex nut was a bitch to get to. In addition, it is very difficult to jam the brake tubing to the nozzle of the bleeder valve. I spent over 90 minutes to complete this job, which I thought would only take 20 minutes.
I also can't believe why people would sell the damn modified CDV. All you had to do was take the stock CDV, and punch out the restricter like everyone says. It was so easy.
The bleeding process was not difficult and it definitely had to be done.
2009 335i 6MT - M-Sport - All stock