Below we will go over the parts needed to replace the radio in you Audi A4 2007 & 2008
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 best radio harness is the Connects 2 CTSAD002 http://enfigcarstereo.com/shopsite_sc/store/html/CONNECTS2_CTSAD002.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. It will also integrate your Bose & non Bose factory amplifier with your aftermarket radio. (radio must have amplifier RCA outputs)
Antenna Adapter
Your car will need is an amplified antenna adapter. Your car has 2 window mounted AM/FM antennas. 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. The Metra 40-EU 55 will also work in this application but it will only use one of your antennas. The Connects2 CT27AA56 http://enfigcarstereo.com/shopsite_sc/store/html/CONNECTS2_CT27AA56.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 Audi specific opening in your dash and convert it into a aftermarket radio industry standard opening.
If you are installing a single din radio the Metra 99-9107B http://enfigcarstereo.com/shopsite_sc/store/html/METRA_99_9107B.html kit is the best one available. We do not recommend this as a double din kit because when used with a double din radio the kit cannot be removed without destroying it, the kit is easily removed when used with a single din radio.
The best double din kit available is the Connect2 CT24AU06R http://enfigcarstereo.com/shopsite_sc/store/html/CONNECTS2_CT24AU06R.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 requires a standard radio installation cage measuring 110mm tall. Pioneer radios require the Pioneer Cage ADT-VA133 http://enfigcarstereo.com/shopsite_sc/store/html/PIONEER_ADT_VA133.html. Most other radios come with a cage. If you are unsure please contact us for more details.