What RPM does the intake flap open when not in sport mode?

[Obioban]

I'm retrofitting the intake flap to my CSL intake on my non CSL M3, which means I'm going to have to control it with a window switch (like is traditionally used in nitrous setups) instead of the ECU. That said, I'd like it to open at whatever RPM BMW decided was best-- what RPM is that?

Thanks in advance!