any ideas what parts i would need and how difficult it would be to retrofit nav to a 182? spoken to a local dealer but they are too thick/lazy to bother and just fob me off. im assuming if i can get the parts nice and cheap and fit it myself it wont be too bad a job so is it just screen, antenna gps unit, cd reader, dashtop, and loom ? or is there anything else i need to bear in mind ?