http://www.peachparts.com/shopforum/diesel-discussion/110577-200d-220d-early-240d-tuning-guide-2.html

Photos of the intake duct in tompaah's attachments. The outer flap with the cut-out for the pneumatic governor tube (#1 in the scheme above) is connected to the gas pedal. The inner flap is free.
Raison d'être for the inner flap - in the attachments in post #21.