You can use Torque Pro on Android (WiFi/Bluetooth) or Forscan Lite on iDevice (WiFi) to monitor boost among a bunch of other things. Check out Amazon to find a well-reviewed OBD adapter. If you get a Scantool device (OBDLink XXXXX), you can use their OBDWiz software on Android as well. DashCommand is another popular tool available for all 3 platforms (Windows, iDevice, Android).