This is just an FYI.

I installed the AEM intake this weekend. It comes with a cylinder-shaped K&N filter which is about 1/2 to 2/3 the size of the stock cone-shaped air filter that comes on our cars. During the install I remembered another board member asking if, say, a JR OEM-replacement filter would fit on the AEM pipe, figuring that the larger OEM-style filters might be even freer-flowing. I happened to have a stock OEM filter, and both JR and K&N OEM replacement filters on hand (don't ask ) so I tried 'em all.

As it turns out, the stock filter and JR filters both have a hard plastic base, which fits only loosely over the AEM pipe and therefore can't be easily secured in place. The K&N, however, has a more rubbery base, and also fits a bit more snugly over the AEM pipe. Therefore it can be easily tightened down using the #48 hose clamp provided with the AEM kit. Of course, it also fits in the wheel well or I wouldn't be mentioning any of this.

Discalimer: I have no data to suggest that the cone filters are in any way better or worse than the cylindrical filter that comes with the kit. This is just another little nugget of S2000 knowledge I thought I'd pass along.

 

It's good that you had an "OEM" sized K&N that you could clamp in place. I only had the JR so I had to "jury rig" my set-up. I had to build up the diameter of the AEM pipe with sticky foam insulation tape, then used duct tape to hold the filter in place. It was a bit Mickey Mouse but worked for me.
I calculated that the "OEM" size of filter had 37 sq. inches more of filtering area than the one that came with the AEM. I figured this can't be all bad.