Removed Headlight

I was reading an issue of Eurotuner magazine the other day and I saw something I've seen several times on E30 series M3's and 3-series BMW's: The inner headlight on the passenger side is removed, and I was wondering why this is? I keep seeing it, and the only conclusions I've come up with were either it's part of a racing specification (two of the cars i've seen this with were qualified to race), or because the turbo is located right behind the hole where the headlight would be and perhaps it provides better airflow. Could anyone help me out, and explain this to me?