The Ford Air Induction System (AIS) fits your 1999-2003, 7.3L Powerstroke with technology that is battle tested in "operation Iraqi Freedom".   This air filtration system holds more dust and soot extending filter life along with filtering more contaminates, all with less restriction than any other conventional pleated filters.  This is one of the best add on air intake systems available for the Ford Powerstroke and because it is designed specifically for the 7.3L diesel Super Duty it fits perfectly. 

No doubt any one who is using this systems knows of its outstanding filtering capability, but may have also experienced the filter minder on the air box showing restriction right after installing the unit.  We have experienced this several times when installing the AIS and originally thought it was due to the filter element being restrictive to air flow.  We decided to conduct a simple test to find out if the AIS filter element was restricting flow or another cause could be found for the filter minder pulling down.  First we reset the filter minder (original unit, not the one that came with the AIS) and drove the truck 1 block full throttle.  The filter minder was pulled down a little more than half way.  Next the AIS filter element was removed and the same test was done with no filter at all.  The filter minder pulled down the same amount.  This indicates that the filter housing and intake tube are causing significant resistance to air flow through the box.

To get more cool air into the AIS box I decided to use the fender opening originally used on the early 99 models for air intake from the drivers side fender.  I wanted to use only cool outside air and keep the AIS from drawing in air from under the hoods as many other performance intakes do.  So an insulated seal would need to be fabricated to seal the fender opening to the back of the AIS unit.

It took some doing and experimentation before coming up with this closed cell foam part that fits into the fender opening to make a seal to the fender and also fit the back of the AIS air box.  This foam piece is longer toward the front of the truck to accomidate the off set of the back of the AIS in relationship to the fender opening.  The foam is rigid enough to hold its shape, but soft enough to compress to make a seal when the air box is installed.  Foam sleeve $23.50.

To get the air into the AIS air box, I located a 3-1/2" hole centered on the "X" shown in the photo using a hole saw.  This is the largest hole that could be sealed without other modifications to the AIS box and its supports.  

This photo shows the AIS installed with the fender seal.  I have been running my system in this configuration for quite some time and it works very well.  The filter minder never pulls down at all and the truck gained performance you can feel seat of the pants.  I have also been comparing the performance of the modified AIS against several other performance intakes, some open, some draw air from the fender and some even draw air from the front and fender.  None of them so far can match the performance and filtering of my modified AIS.  We are now considering offering the foam connecting tube to our customers who have choosen the Ford AIS and possibly including it in the AIS systems we sell.

Of course we can never leave well enough alone.  We have manufactured a prototype filter element holder to fit the AIS air box that holds a 2-stage foam filter element.  Testing this element against the Ford paper AIS element shows no noticeable differences between the two.  The foam element also does an excellent job of stopping dirt with plenty of surface area and has the advantage of being washable for reuse.  At this time we have no plans to produce this filter holder as the AIS filter elements are good for extended use, but may consider making it in the future should there be a demand for it.