The engine sounds in this video are real SoundRacer V12 gadget and SAAB 9-5 Aero Turbo BioPower, and no sounds are added but some exterior clip are edited into interior recording.
If you want a powerful sound in your Saab, you do not need to buy this device because you can download a SoundRacer free Android application from Google Play and connect it to the car via the OBD connection (via Bluetooth OBD II device, as ELM327).
Here is Ferrari V12 engine sound in Saab 9-5 NG:
SoundRacer Android app
And that’s not all, the sound Ferrari you can replace with a few sounds other machines, in this case it is a Harley-Davidson engine sound in new Saab 9-5 :)