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Go for a custom ipad mini install Mate
http://forums.justcommodores.com.au/ve-holden-commodore-2006/210818-ipad-mini-install.html
The touch screen HVAC controller is fine but IMO it is over priced and requires your attention while you drive (not very safe).
Remember you could sell your IQ system for quite a nice chunk of change and probably offset all of your costs.
Or you could custom fab a bracket in front of your IQ system and mount the iPad there talking to your HU via USB.