CobbTuning.com - Service Bulletin: 07 WRX/STi Overboosting with Catless Exhaust
Resetting the ECU won't fix the problem as it's a mechanical issue. Changing to a different bcs such as a 3 port as newtothegame suggested will help to hold boost better (must be retuned for). You can port the wastegate which seems to help solve this issue with the 2.5L engines. As for the restrictor pill, you can see in a diagram in the link above that it sits in the vac line from the T fitting to the turbo compressor housing. It's a little brass pill with a small hole in it designed to help hold stock boost levels. COBB recommends when you upgrade the turbo to drill it out to a certain size, but I recommend a 3port bcs and retune to start.