As vstech said the Stock Air Filter can allow more flow than the Engine needs.
The other intakes claim better flow but who really knows. And, it is also unknown if the Filter used Filter Better or worse than the Stock one does.
I did this to keep the Blowby Oil Vapor away from the Air Filter Element; not for more Air Flow.
Washable Air Filter and Intake Mod , With Larger Breather
Washable Air Filter and Intake Mod , With Larger Breather - PeachParts Mercedes ShopForum
Hot Air Intake My comments in the below Thread of my test. Post #5
"I never posted this information as I wanted to try it again.
I have a digital Thermometer with a probe long enough the I put it under the hood at the end of my air filter horn (Federal air filter housing) which would be about where one of those Cone type filters would be
under the hood and I ran the car on the Freeway to get it hot and drove around town and sat at some long Traffic Signals. I also put the probe all the way up front where the cold air would go into the air filter and drove around again.
I was surprised to find out that while you are moving even in slow traffic the outside and under the hood temperature is not significantly different. However, when you idle the under the hood temperature went up from the 76 degree outside temp to 98-110 degrees under the hood.
My conclusion is that you do no harm by having the end of the air intake system under the hood as it only made a differance when you sat at idle. When you start moving there is enough air flow that you get the colder outside air anyway.
If you want to try the experiment youself (cheaper than a new intake system) I bought the thermometer at Target and it has a 36 inch long steel braided covered wire. You are supposed to stick the probe in what you are cooking in the oven to measure the inside temp of it and run the cable out of the oven door and the Digital display has magnets on the back to stick to you oven/car hood. I believe it cost around $16.
Get someone with good eyes to ride along with you to do the reading of the thermostat."
Replacing Stock Air filter with straight flow cone k+n? - PeachParts Mercedes ShopForum