 Last month the folks at AEM were nice enough to send me an intake kit for my '99 TJ with its little 2.5L 4 banger. The kit consisted of a new air tube, conical filter, heat/dust shield and assorted parts for mounting it under the hood. The instructions provided were decent so I won't bother to go into a detailed, step-by-step install description here, but will hit some of the basics of the install.
 Removal of the old air box and associated parts and the install of the new equipment is fairly straight forward and can be accomplished with basic tools… a socket set, a pair of pliers, an open end wrench set, and a screw driver or two. If your Jeep is a few years down the road and as filth encrusted as mine is you may have a few frustrations here and there, but nothing that is a major deal (with one notable exception, which I will get to).
When I took off my old air box and such I noticed that the standoffs for the factory tube were broken clean through. So needless to say, the install of the AEM equipment was a bonus for me since apparently I had parts that needed replacing anyway. I also had some slight difficulty getting the bolts that mount the filter box to the fender well off... the head on the front one snapped on me. Luckily though the AEM equipment does not use this hole, so I was able to just leave the bolt stem in it.
 Following the instructions provided makes the install of the AEM equipment quick and simple, but it's my suggestion that AEM look at slightly re-engineering how the front of their heat/dust shield attaches to the Jeep. Currently it uses the upper passenger side bolt for the radiator. The problem with this is that when the heat shield is in place it makes it extremely difficult to re-insert and tighten down that bolt again. The shield boxed the bolt in (see picture) so that the best I could manage at a time was about a 1/16th turn on the open end wrench at any given time... which means it takes forever to get that bolt snugged back down. This was easily the most time consuming (and frustrating) part of the install... but over all it isn't a showstopper issue.
 One other thing I noted during the install was that the tabs on the air tube that secure it to the fender well could have used to be a touch longer. My Jeep has a 1" body lift without a motor mount lift, and as such I had to fidget with the tube a little to get enough of the mounting tab under the fender well washer and bolt to hold the tube securely. If I ever get around to installing the 1" raised motor mounts I have had in the garage for over a year now, that problem may go away however. But, it would be nice if AEM was a little more generous on the length of the mounting tab so as to accommodate those with body lifts and stock motor mounts.
Now for performance… did it make any difference?
 My original plan was to get the Jeep on a dyno before and after the install but unfortunately I couldn't find anyone willing to test the Jeep. Apparently around here shops use to dealing with sports cars are a little intimidated about dealing with a vehicle with big knobby tires. Two of the shops I talked to all said they could do it if had smaller tires with a less aggressive tread (I run 33" Swamper TSLs). The third said they could do it but would not be responsible for any damage that might be incurred, and wanted over $500 to do it. So unfortunately dyno testing just wasn't going to happen.
As for "seat of the pants" testing…. It sure seems a like the 4 banger has a little more pep to it. I don't really see much of a difference down in the low RPM range, but it seems to jump through 2500 to 3500 rpm a little quicker. And I did notice that the engine note seems a little throatier.
 On the road the Jeep seems to run a little better at highway speed now with the AEM equipment in place. And let me tell you.. when you run 33" tires on a 4 cylinder engine any help you can get is much appreciated! As for offroad I had some concerns about an open filter during water crossings and such, but so far it hasn't been an issue. The quicker jump through 3000 rpm certainly can't hurt on hill climbing either! I noticed I was able to get the power up a little quicker while climbing where a small increase in power can make a big difference when there isn't much of a "launch pad" at the bottom of the hill.
All in all, the AEM kit is a very nice product and seems to be very sturdy and built to last for years of service (I was impressed with the construction of the tube, including the material composition, welds and mounting equipment). It's a decent choice to help add a little bit more "ooompff" to the 2.5L... something I think any 4 cylinder owner can agree their Jeep could use.
If you would like to purchase an AEM Intake Look for your application below:
AEM Brute Force Air Intake System, Liberty, 2002-03 with 3.7L V6
AEM Brute Force Intake System, TJ, 1997-03 with 4.0L 6 cyl.
AEM Brute Force Intake System, TJ, 1997-02 with 2.5L 4 cyl.
AEM Brute Force Air Intake System, Grand Cherokee, 1993-98 with 5.2L or 5.9L V8
For more information or a list of applications you can visit AEM online by clicking their logo below:
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