Hi Everyone,
i live in Italy and i have just bought an Opel GT, that is twin sister of Solstice and Saturn Sky.
I write here because my car isn't really popular in Italy or Europe and there isn't any specialized forum where i can ask some tips.

I want to replace the monsoon headunit with a Pioner Avic, but i'm quite confused about what exactly i need.

I have figured out that i need a steering wheel adapter and some adapter to connect the audio with the new headunit, exactly i need the gmos lan 04, but since my car hasn't Onstar service, what exactly does this adapter?
If i do a direct wiring using some diagram, what i can loose?
I know are noob questions but i would like to do everything correct.

Tnx for help