For a full airbox mod you would just about remove the entire middle "layer" of the box. You would cut out all but maybe a 1/2-3/4 of a inch all the way around the inside of the box....then fill the box with black filter foam and TADAAA!! your FULL AIRBOX MOD is done.
In this pic...the red area needs to be removed.
#1 is the outside of the airbox
#2 is the area to be removed
#3 is the bottom of the airbox
First I want to say thanks to the info on the air box mod. I did it on my '99 and it definitely gave it a bit more pep. Second, in order to do the mod, I found it highly effective to use a Roto-Zip bit in a drill. It makes for a very clean cut and only takes about 3 minutes to do the whole thing. Sure beats the hell out of trying to do it with a utility knife !!!