For performance mods, you will need the COBB AP. This includes intakes and DP. It's more than running like sh@#. The stock ECU will make adjustments to timing and so forth that could lead to engine damage and/or failure under aggressive driving. At least that's how I've approached it as a first time LGT owner. Others can add their experience that have been moding Subies for a while longer
Summary - Balance performance mods with planned and simultaneous ECU map changes. The COBB website has a good list of do's and don't for mods.