airboxes

Heard a couple of people talk about drilled airboxes... What are these? How do you do it and why do some say they are better than induction kits?

How have you fitted your cold air feed to the box and made it air tight - any pics would be much appreciated. I've done a lot of searchy searchy on this and i've seen a couple where people have hacked big holes in their airboxes, is it possible without doing this or does that restrict airflow...