I have heard of people drilling holes in to their airbox to open it up. I was looking at mine last night debating if I should add some holes to it. But I don't know if that will affect the jetting that has already been done to it.
When I bought my bike, I had the dealer add a full Muzzy, K&N filter, and jetted my carbs. Would opening up my airbox affect the jetting that has already been done. Is it worth it considering I have a K&N and Mull Muzzy?
I'm always looking for a little bit more.

 

Do you have the lid on?

 

I will leave this for JRock.

Back on topic.

If the lids off, drilling will be a waste of time.
If the lids on, take it off.
There is a half way option of fitting a KDX snorkle.

And yes, a rejet will probably be required.
Maybe not.
Pull the lid and try it.