Below we will go over the parts needed to replace the radio in you GTI 2006-2010, Jetta 2005.5-2010, R32 2008 & Rabbit 2006-2010.
Radio Harness
The first thing you will need is a radio harness. The radio harness will connect the power and audio wires from your new radio to your car without cutting the factory wiring.
The basic radio harness is the Metra 70-9003 http://enfigcarstereo.com/shopsite_sc/store/html/70_9003.html. This harness will connect all your speaker leads (whether amplified or not) between your new radio and your car. It will also connect the constant +12v & ground power cables. Since your car has a can-bus system the ignition, illumination, reverse & Vehicle Speed Sense / VSS wires have to be located in other parts of the car.
The best radio harness is the Connects 2 CTSVW002 http://enfigcarstereo.com/shopsite_sc/store/html/CONNECTS2_CTSVW002.html. This harness will give you all your speaker leads, constant +12V, ground, switched ignition +12 power leads. It will also give you your illumination, VSS / vehicle speed sense, reverse (gives you a signal when you put the car in reverse to activate a back up cam) wires. If you add the radio specific steering wheel control lead this adapter will also enable your factory steering wheel controls to work with your car without any programing or additional modules.
Antenna Adapter
Your car will need is an amplified antenna adapter. Your car has an amplified antenna system. If your car came with the single CD radio you have a single roof mounted antenna system. The Metra 40-EU55 http://enfigcarstereo.com/shopsite_sc/store/html/40_EU55.html antenna adapter will convert your factory antenna into the aftermarket radio industry standard Motorola antenna connection. It will also provide power to your antenna amplifier . You must use the amplified antenna adapter or you will have a severe loss in reception. All other radios came with a dual window mounted antenna system. The Metra 40-EU 55 will also work in this application but it will only use one of your antennas. The Connects2 CT27AA25 http://enfigcarstereo.com/shopsite_sc/store/html/CONNECTS2_CT27AA25.html antenna adapter is a better option because it will use and power both of your antennas.
Radio Installation Dash Kit
A radio installation dash kit will take the Volkswagen specific opening in your dash and convert it into a aftermarket radio industry standard opening.
The best kit available is the Connect2 CT24VW03R http://enfigcarstereo.com/shopsite_sc/store/html/CONNECTS2_CT24VW03R.html. This kit has a rubber like coating that matches the factory dash board better then any other kit we have ever seen. This kit will take a standard single din radio as is. If you are installing a double din radio you will also need the Connects2 CT23UN01 http://enfigcarstereo.com/shopsite_sc/store/html/CONNECTS2_CT23UN01.html radio installation cage. This is the only cage we know of that will fit. All the aftermarket cages we have seen are 110mm tall and this one is 100mm tall.
We offer 2 other kits. They are made of a much cheaper plastic that does not match the dash but they they can both be used as single or double din kit. The American International kit does not come with a double din trim ring and must be cut in order to fit a double din radio. The Metra 99-9011 has recently been coated with a spray coating that closely resembles the factory dash. We used to recommend the American international kit over the Metra kit but since the Metra kit has been coated we now think that it is a better looking kit and prefer it. Metra 99-9011 http://enfigcarstereo.com/shopsite_sc/store/html/METRA_99_9011.html & American International VW-K1017 http://enfigcarstereo.com/shopsite_sc/store/html/AI_VW_K1017.html.