This is a simple home made air filter intake mode for your 7.3L Powerstroke. I am doing this mod on a 97 F350 but I'm sure this will work on the SD all the same.

Begin by removing the old air box and throw it in the trash or sell it (mine was blown up by a ether overdose).
You will need to keep the 2 OEM sections of rubber pipe that go from the turbo to the second section of rubber pip that is 4 inch on both sides.
You will need a 4 inch piece of 45 degree exhaust/aluminum/steel elbow pipe, I got mine for $28 shipped to the door off ebay (4" OD 45 Degree Bend Steel 42247 )
Then just snug one end of the elbow into the OEM pipe and the other into your filter of choice provided it has a 4inch ID fitting. I use a NAPA 3667 or 43667, Amazon.com has them at a great price just look up the number.

Tighten up the hose clamps and there you go, you will probably need to improvise something to hold down your filter element.

Costs:
Filter $42
45degree ebow $28
So $70 for a easy air filter upgrade.

I read that the T clamps will provide better clamping at some point I will upgrade my OEM clamps but for now they will do. I also read to put some vaseline on the connection points to help get a better fit.