Disregard any mention of dates, they are rubbish, all models (facelift and non-facelift) are equal re dashboard etc.
You can install any 2-din headunit you want. 2 din facias are available from most car hifi shops.
Steering controls are not CAN, but simple analogue voltage outputs. You will need an adapter though, most stereo supliers provide them for their HUs....
Do a search on this forum, there are tons of subjects on this. It's all fairly straightforward. Have a look here f.i.
http://www.alfaowner.com/Forum/ice-andamp-blueandamp-me/153629-how-to-install-aftermarket-headunit-guide-147-156-and-gt.html

 

Had this put in our GT last year,works well with the Bose and retains steering wheel controls.....

Made by Kenwood and we're really pleased with it

 

Thanks gents that's really useful. I will be ordering everything I need this weekend and I welcome more good advice!

One other thing, are the steering wheel controls actually CANbus or not?

 

As said before, NO. But you will need a audio-brand specific adapter

http://home.planet.nl/~jwq/temp_gta/elearn/steeringComponents.pdf

 

Alpine does everything and good sat nav including Bluetooth

 

Read this thread to see a cheap Chinese double din unit in my son's car.

http://www.alfaowner.com/Forum/alfa-147-156-andamp-gt/866746-double-din.html

 

Being Android it does everything you can think of and more. £208 all in. You can either buy adaptor leads or use bullet connectors to make the 3 or 4 changes caused by Alfa being none standard.

Blue tooth including phone book transfer.
Blue tooth music
Sat Nav with free maps
In built Wifi
Touch screen
Decode every music encoder including, my favourite, flac
Reversing camera facility
Micro SD cards one for maps and one for media
4x full size USB lead connections
Connect to your phone via wifi and use google maps if you choose
Thousands of compatible Android Aps
Region free DVD.
Fast and smooth operation with no delay between aps and seems to multi task flawlessly

 

@ kandlbarrett

I have looked at your suggested unit and I want to buy it. My only question regarding this item is what do I need to do to get the steering wheel controls working? Did you get it working in your son's car?