Poor Man's Ram Air
This mod brought to you by the cheap and warped genius of Tim Gahagan.
Now don't laugh!
Remove the silencer cone and air chamber from inside the driver's side front fender. This will probably require that you remove the tire and wheel well liner so that you can gain access to the part. You also have to temporarily remove the main air box in order to remove the mounting nuts that hold the silencer in place within the fender.
Remove the silencer horn, then saw off the plastic key that forces you to install it in only one way. Then you can turn the horn around (this makes the horn point inward and down). Saw off the horn leaving around a 1 inch lip. Remove the silencer horn constriction after this modification is done.
Now for the air box modification.
Take a 1 gallon milk jug (yea don't laugh it gets better), cut it in half diagonally and cut it so that you can form it into the air box and create a scoop that will force air out of the horn to the filter box instead of back to the pointed end of the box.
I used rivets to secure the milk jug, leaving a little lip of the milk jug hanging out of the box at the bottom of the hole that goes to the filter box. This is curled around, and re-attached the foam seal to it so that it will better seal when box is secured back in fender.
Now get a vacuum hose (I mean the kind that would hook to a SHOP VAC the 2 inch kind) (I told you don't laugh, that is would get better.) Cut one end off of the hose, this end you can secure to the horn (where you cut off the horn leaving a 1" or so lip).
Run the hose up and around in the bumper to the front to the grill.
I placed mine very low (read further for problems), in the bottom slot below the headlights and between the fog lights (didn't want to lose my fog lights).
Ok more junk to get, go get the vacuum scoop that is roughly 4 inch long and 3 inch wide (I think it is one used to suck up water, it has a small plastic squeegee/brush in it). Rip out the brush. I made a 90 degree "L" bracket one side with a hole which will allow me to screw it into the mount that is for the transmission cooler. The other side of the "L" bracket is wider and this I bent at and angle to allow the scoop to set flush to the bracket and the mouth of the scoop to be vertical (allowing for the hose connection to point upward) Now route your hose and plug in.
I am not a dynamometer man or anything but I read that it is anywhere from 5 to 10hp gain. Ed. note: very dubious claim.
I shaved a tenth off of the quarter and can creep away from stock SHOs (autos, mine is an auto) on the highway, around 95mph to 100mph you can really feel a difference in the pull of the car.
Be noted that this could possibly suck up rocks, cats, dogs, gravel, sand, dust, water, or lettuce.
I have found that the air box needs to be cleaned regularly (every 2 weeks or so) and that when I drive up against the concrete wall on the interstate it sucks more dust.
Sand and dirt is my only problem. Water has not been a problem for me, even the day I drove 65+ when it reined 12 inches in an hour. The filter was somewhat damp but not bad.
To monitor water, I rigged a circuit to notify me if the filter got wet, and a different one if water was pooling in the filter box. The second warning has never come on. (Check your 150 and 151 science project for water sensor circuits)
For what it is worth (20 bucks) it seems to me to add about 5 hp.