Originally Posted by MADDOG
Most of the data I've seen leads me to believe that almost all CAI's flow about the same CFM.
Remember, your intake manifold and intake piping will only hold so much air and the engine only uses so much air during a combustion cycle so higher flow probably isn't the key data point.
However, clean air flowing through a smooth pipe with few transitions, hard curves or right angles will improve throttle response (which is the improvement most folks feel) is key.
One last thing to consider is that most CAI's draw air from inside the engine compartment. That's heated air. Using a system that draws air from a stock cold air inlet or utilizing some other method, is preferable ("cold" air intake - get it???) but not absolutely necessary.
The combination of volume, smooth transitions and inlet air temp are the three basic areas to consider when picking a CAI.
Thats why I got my BFI, smooth transitions, Huge volume(6" inlet opening) and when combined with an Airram JetStream scoop it gets plenty of fresh cool air. Good luck with your choice.