Quote:
Originally Posted by Wires
Stock:
- has a flap on the exhaust manifold side that spring open should the front intake get plugged with snow.
- foam sheet clipped to the bottom to keep dust/sand/bugs trapped in that grid at the bottom.
M box:
- no foam
- no snow flap
- cut out front side with the red bezel
The m-cutout would potentially suck hotter air from the engine compartment instead of cold air from the actual inlet. I'm guessing you would get more intake noise as well.
I just yanked the foam from mine, and put in a K&N filter. You could just cut a similar hole in the side of your stock air box and get almost the same thing for free. If you fail at the cutout, buy the m-box to replace it. 
Oh yeh, if you want extra power, you obviously need to wrap the opening in red. That's good for 20HP. |
I cannot see BMW designing a "Performance" part that would be so poorly engineered to suck in hot air from the engine side
