[Nhe261]

I am a new bimmer owner, forgive me if i say something wrong.
Just got a 2008 E90 335i with only 40K miles, very excited, not start to mod yet.
Today i checked the stock air filter then i found the filter is only half very dirty and the other half is very clean. then i notice there is a bump under the filter in the air box, to my eye, the bump is touching the filter bottom. that means the air has only half surface to pass through.
TO prove it, i removed the air box and looked from the air suction hole, the gap between the filter and the bump is less than 1/8”, and only half area is open to the air.
I took some pictures using smart phone but havent figure out how to paste here. Maybe somebody can help?
that can explain why lots of people doing DCI and notice the improvement, that also can explain why open the air box top cover can gain 10HP directly without any tune.
The first mod i will do is the open box intake. TWIN TURBO NEEDS FREE BREATH!
Did anybody think about covert the air box top cover to a filter? T hen we will have two filter and two air sources, even it is hot air but better than choke. same idea as HELIX air box, half hot half cold.