Nav conversion can be done as a DIY - I have instructions and software to reprogram the nav, or hotwire on this forum offers a nav upgrade service whereby you just bring the car to him, and he does everything for you.
Can you provide the wiring instructions / pinouts when converting from a JAP DVD Navi Sys II to a MK3. I have the necessary MK3 unit , SW (NavCoder) and ODB II cable.