This is an ol trick that has been created by fellow stang owners and f-150 owners. What you do is disassemble the air box. Take a 3/8" drill bit, of course when you do this remove the air filter as well, and drill as many holes as possible. This should create a " swiss cheese" effect in your box. Put everything back together and whalla! Free intake. You just increased your air flow to about 85% and it has been dyno proven to work. My buddy did it in his stang and got about 12 hp to the wheels!!!! He also added the K&N air filter as well and it definitely helped him out.
Not that I agree with this, but the area the holes would be drilled is below the filter so the air still would be filtered, but the filter would need to be changed more often, and this mod would increase the chance of more water to be sucked in if the box gets under water.
2004 GC Spec. Edit. V8 4x4 Quadra-Trac II. Bright Silver Metallic Clear Coat, 4" lift, RE shocks, adj. JKS CAs all around, 265/75/16, 10 ply., Maxxis Bighorns, ProtoFab winch bumper, Vortex 10,000 lb. winch, dual OME steering stabilizer, Rockyroad rockrails, skids, JKS Discos. Addco front & rear sway bar, & Aussie locker. Next year? : Rear bumper with tire carrier.