There are three main things that primarily control the boost on your 1.4T.  The ECM, the bypass solenoid, and finally the wastegate diaphragm. This is the part that holds the wastegate flapper closed until desired boost is achieved, then it releases exhaust into your o2 housing/downpipe to maintain that desired boost.  The factory one is known to fail and is also known to not be able to hold desired boost to redline.  This is an aftermarket replacement bypass valve that has increased spring pressure which will hit your desired boost quicker and maintain a more consistent boost for higher RPM power (due to keeping boost PSI higher to redline).  

Important: This product will help avoid a P0299 "under boost" code, but will also increase your chance of getting a P0234 "over boost" code.  Depending on how your car is tuned, this will most likely require a PCM file update.