Looking at the Tactrix website, there are two cables there, the "OpenPort for WRX and drive-by-wire vehicles" and also the "OpenPort for Subaru Drive-by-wire vehicles". From what I can tell the only difference is the WRX-specific one comes with a reflash connector.
I have an 05 Impreza RS, which was the first year for n/a Impreza's getting drive-by-wire. The OpenPort for Subaru vehicles only lists the turbo models as compatible, but it looks from this thread like other Impreza owners have used this thing without issues, anybody have anything to say about my application before I order one up?