There's a torrent for RT4 RT5 Navidrive systems with maps of Great Britain and Ireland, 2014.

It is an ISO file, to be burnt to CD. Then loaded while the engine is running.

Hash: DA5511CFB6707FB9B848B8E5604A81DC5F840146

Magnet Link: magnet:?xt=urn:btih:3JKRDT5WOB73TOCIXDSWASUB3RPYIAKG

A bittorrent client should understand either the hash or the magnet link.