Mike, I have the rectangular K & N filter that fits in the factory air filter housing. Many years ago, I did time trials and autocrossed my euro 190D, so I explored every possible mod to improve performance. I timed acceleration runs at Summit Point track comparing the fresh K & N, a new MB air filter, no filter at all with the housing in place, and no filter at all with the housing completely removed. There was no significant difference, just more noise. I did laps comparing K & N, new MB filter, and no filter all with the filter housing in place and again, very little difference. You might try replacing the plastic hose between the scoop and the housing with a constant sized diameter hose to make you feel better about unimpeded airflow, but with only 76 horsepower or so, little changes really don't make any difference.

Andmoon, the vent hose from the valve cover does not go into the air filter housing, but connects to hoses that go directly into the intake manifold.