Name of the song in Purgatory?
I could stay for hours in the purgatory bar in the citadel just to listen to the music.
What's the name of that song, so I can put it on my iPod; on repeat.
Is this the song you're referring to?
It's "Staggered Injection" by Ekstrak. It was also on the NFS: Carbon soundtrack, and you can find it on iTunes, Google Play, or Amazon. On that OST, it was just called "Staggered" - they sound the same to me, but you might preview the track to make sure it's the same (or at least close enough that you like it the same ;)