AWE Intercoolers
(AWE Website Link)

In the first picture below, you can see the passenger side S4 IC, RS4 IC, and the AWE IC.  The frontal area on the RS4 IC is approximately 7"x9" (63 sq in), where as the AWE IC is approximately 8.25"x8.25" (68 sq in).  But the most noticeable size difference is in the thickness of the core.  The RS4 IC is ~2 3/8" thick, where as the AWE IC is ~3.5" thick. This makes the volume of the core's footprint on the RS4 to be 149 cu in, where as the AWE IC is 238 cu in.  Also, the design of the RS4 ICs is Tube & Fin, while the AWE ICs are Bar & Plate.  Also note in the pictures that the AWE ICs come with custom made fiberglass shrouds that are designed for their ICs.

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The below plot is Intake Air Temperature readings taken first (red) with S4 ICs, then with (blue) AWE ICs.  I chose this "before" (S4 ICs) graph to use since it was the closest I had to match up to the initial IAT at ~3200 RPMs (45mph cruise control in 3rd gear).  This makes it easiest to compare the curves of each set of graphs as the car is going WOT to redline.  As you can see below, the AWE ICs do a much better job of getting cooler air into the engine than the S4 ICs.