So I installed a clarion pop out touch screen in my turbo (fitment and Heat are big issues as the factory unit does not go in as deep as after market units or atleast the fancy ones) The stereo store told me they could get an adapter but I'd have to pay for it before hand and it would be non returnable
. Ha haha no way in heck am I agreeing to buy something I can't hold in my hand or even see that cannot be returned. My solution was rewiring the entire cars audio system starting at the fuse box. I used 16 guage speaker wire for automotive use and used a paint pen to mark the ends off all wires. I ran my own power wire both to and from the fuse box in place of the factory wires and then tried to use the factory ground. That was not a sufficient ground for my unit so I ran the same type of wire as I used on the power wire but in black ran it to the back side of my glove box mounting bolt after I buffed it and the firewall raw and then covered it in dielectric grease. I know kicker sells sticky insulating tape for plastic panels if you put any sub in a mk1 there is a very fine line between good sound and rattle trap. I was getting the dash to rattle with a pair of kicker 4" rounds. A plus side to upgrading your stereo unit is most decent quality units nowadays allow you to tune the deck for whatever speakers your using regardless of impedance. The real challenge is getting 16 guage wires into the hatch in place of the tiny factory ones which most likely have broken from years of opening and closing (I am still trying to get the wires into the hatch and have been unsuccessful but I did find my wire snake and am yet to try with it). 16 guage is total overkill but leaves allot of room for future improvement. I noticed when I finished my deck installation my instrument panel no longer would dim with the dial it was just on or off. With that I was able to get a pop out touch screen/DVD player, navigation, Bluetooth, usb capability with satellite radio 
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