The object here is to increase the airflow available to the intake.

(This information seems to be getting lost and I did things a bit differently than some, so here's my modded airbox.)

You will need:

1" hole saw, Jigsaw or disc cutter, small hand grinder, drill w/1/4" & 3/16" bits , Popriveter 24" square piece of thin belting, 3/16" poprivets w/washers.

What I did:
You will have to first remove the airbox. Cut or drill the rivet retaining the "venturi" inlet tube, and pull it out (to get it out of the way). Use the hole saw to cut the corners, then cut out between them with the jigsaw or disc cutter.

Clean up the edges with a file and or knife.

The belting is then wrapped around the box , trimmed to fit the radiator support , remove the excess , and riveted in place using the washers to hold and take the pressure off the plastic.

To aid the flow of air I "Swissed both the front airbox bracket...

....and the headlight bracket...

  To modify the headlight bracket , I marked the area through the hole in the radiator support then, remove the headlight assembly by lifting the retaining slides and detach the bracket. Drill holes through the "honey comb" in the marked area. Then use the grinder to remove 1/4" to 5/16" carefully from the back of the bracket to reveal the openings, A little work with a knife will clean up the squares.

This mod is best because of the price! It does make a difference and has been no problem in deep water.