Originally Posted by e34m5
Let's see. BMW spends hundred of thousands making sure these things are set up right, but some one believes they can do it better.
I've tried CAI's on any number of BMW's and to date none worked better than OEM.
There is more to a CAI than where the air is drawn from. Length, air turbulance and many other factors come into play.
To really make a difference you would need to actively cool the intake air.
...adding: BMW says the Z4is makes 15hp more than the 335is due to a better intake.