Your factory 2.9TT water-cooled intercooler relies on a severely undersized core volume of only 1,870cm³ and shared engine coolant to regulate air intake temperatures. Even in completely stock form, spirited and normal driving leads to significant rises in air temperatures, resulting in power reduction. The cooling benefits of water are not enough to compensate for the tiny intercooler size, coupled with the increased water weight and heat demands on the radiator.
The iE intercooler adopts a traditional air-to-air design, divorcing the core from engine coolant. This strategic shift substantially increases core volume to 18,500cm³ (10X larger!), providing an extensive surface area for efficient heat dissipation. This separation delivers unmatched cooling for even the most serious builds, less water weight, and allows the factory radiator to focus on keeping the drivetrain cool.