Hi Vulcan, nothing extra to purchase. comes with all leads including gps receiver, tv aerial and microphone. No mods needed.Its plug and play really, a multi-plug and another lead for the steering wheel controls. Sat nav is hard drive based so a lot quicker than a cd/dvd based one. The maps are stored on a micro sd card and were updated for free last year. It can read various map formats when set up including garmin etc but I have just used the ones that it came with.