Not Holes in the airbox, but.........

[Empty Pockets]

I understand that I don't want to put holes in my airbox because that will introduce hot, engine compartment, air. If I want better performance I will want more cool, more dense, air from up front. I hear that there are some ways to put a larger extension to replase that snorkel in front of the airbox.

Any ideas...any good results? Thanks