Think of Foam Filter But duno where it goes

[CMF_S2000]

I'm thinking getting a foam filter for my march. But I duno where it should go?? Do I remove the factory airbox and smack the foam/pod directly in its place?? If so do I have to watch out for inlet diameter etc etc?? Many help would be great thanks.

 

[CMF_Snoopy]

http://www.micra.com.au/information/nissan-micra-articles/cold-air-intake.php
Hope this helps