Has anyone ever done the stock airbox mod

Not even sure what that is. I have a BHAF on mine.

Is that were you cut holes in the sides of the bottom part of the air box?  

If your are going to keep using the oem air box its good to shave the lip on the lower box just a little. It helps the upper section seal better/ tighter to the stock filter rubber seal.

2 hours ago, trreed said:

Is that were you cut holes in the sides of the bottom part of the air box?  

People would do something similar in the 6.5TD community.  I never did it when I had mine.  They called it "Swiss cheesing" the air box.    

1st gen guys do it.

 

Never really heard of 2nd gen guys do it.

I would rather install a BHAF that even attempt to make the stock box work.