Audi TT 225 Aftermarket Stereo Installation?

I have a 2001 Audi TT 225bhp with the standard manufacturers stereo system. I'm looking to buy a aftermarket stereo from www.caraudiosecurity.com. Preferably one with aux cable included so i can attach my iPhone.

I'm just wondering if it is a simple swap such as removing the power leads, arial cable and connecting them to the new one. Or will there be some wiring needed?

If your car has remote (steering wheel, etc) controls for the stereo, or a remote display, either on the instrument cluster, or dash, then additional wiring is required to maintain this functionality. The supplier/installer of the unit will be able to advise.