Scion tC: Turbo or Supercharger?

I have a 2009 Scion tC TRD edition,the only bad thing is that it is AUTOMATIC. I wanted to get it a little bit more power...acually want to try and get it to a lot of power eventually, and I was wondering what would be better? A turbo on a Automatic Scion tC, or a supercharger on a Automatic Scion tC (if they even have superchargers for them anymore for them since TRD quit making them.) And if I do get one or the other, what transmission or other engine modifications would I have to do? Thanks