The CTS MK2 TT/TTS 2.0T Direct Fit FMIC Kit is designed as a drop in replacement for the OEM front mounted intercooler (FMIC).  That means you can install this kit without any trimming or modification of the bumper.  The OEM FMIC is adequate for stock boost levels, however once boost levels are increased by way of ECU upgrades/chipping the OEM FMIC struggles to keep the charged air temperatures in check.  Higher charged air temperatures can result in boost cut and timing pull, both reducing the amount of power your vehicle produces.  

The CTS direct fit FMIC uses a high efficiency bar and plate intercooler core, which aids in reducing pressure drop.  Reducing pressure drop means that your turbo will not have to work as hard to make a given level of boost.  If your turbo makes 30psi of boost pressure in the turbocharger, and your intercooler has a 10psi pressure drop then the boost measured by your ECU would be (30psi - 10psi) = 20psi.  With an efficient FMIC like the CTS direct fit FMIC your turbo does not have to work as hard to reach desired boost levels.  This is beneficial in two ways, the turbo life expectancy is increased due to more efficient operation, and boost leaving the turbocharger is cooler and more dense resulting in more power to the ground.