The thickness allows less resistance to flow (pressure drop) due to the increased volume and the larger surface area cools the intake charge more. Both are important. I just can't tell any surface area difference from pictures I have seen of the ssautochrome and reputable companies (APS, Perrin, ETC.). Both seem huge compared to the stock STi intercooler. If anyone has a side by side of a ssautochrome and a reputable aftermarket intercooler it will help clarify this for me. On ssautochrome.com they compare to a STi intercooler and it is both thicker and larger.