OK...straight from Motec themselves....the OE pnp will NOT work on the MY06 STi. The upgraded version (mid next year will).
Yes a standard (non OE) Motec box (eg M800 non OE) will do the job BUT would need to be wired into the car...in other words, cut off the standard plugs and re-wire the harness to fit the standard Motec box...which would be a bit of a pain, but if people want to go down that path, OK.