Richwig is your stereo a RCD300 and any chance if you get a sec you could link me to the item you bought?
I used this kit at add aux input to the rcd300 that came in my 06 GTI.
http://www.dynamicsounds.co.uk/connects2-ctvvgx004-vw-eos-golf-passat-polo-jetta-aux-interface-adaptor-p-8770.htmlConnects 2 Aux Input to OEM Adapter Interface for VW Passat/Golf/Touareg/Touran/Transporter with Delphi, Blaupunkt, Delta 6 Double Din,RCD200,RCD300,RCD500 head units. This Aux Adaptor Interface is compatible with following car models:
VW Eos (2006 onwards)
VW Golf (2003 onwards) MK5
VW Passat (2003 onwards)
VW Polo (2004 onwards)
VW Jetta (2006 onwards)
VW Touareg (2002 onwards)
VW Touran (2002 onwards)
VW Transporter (2002 onwards) T5
Please note: This item is NOT compatible with stereos that have the 6 CD Player built into the stereo.I actually used a longer phono to 3.5mm cable (cheap on ebay etc) so it can reach to my iPhone suctioned to my windscreen running the tomtom app and playing music. When I do this the cable can runs between glove box door without any stress to it as cable is relatively thin and its tucked away the rest of the time.
Fitting took approx 45 mins. No need to cut anything. The aux cable can be feed by hand across to the glove box, just make sure you remove the owners manual and you should be able to see the cabe and pull it in to the glove box.
Lots of videos showing how to remove radio on YouTube.
http://youtu.be/Ea8nos5SbLwHave clean cloths/rags to protect your gear knob etc from scratches.
I did buy plastic trim tools on eBay. I took things slowly, watching each step on my ipad before proceeding. Take it slow and don't force anything and you'll be fine. I also put sound deadening tape on the box and wires to avoid vibrations and rattles.
I plan to upgrade the head unit to RNS 510 or 310 but this aux input has worked a treat on continental holiday drives over the summer etc.
Good luck