Hi I have a Nuvi 40 which has Sensis Whereis, CN Aus & NZ NT 2012.20 map on it, can I change it over to the newer Navteq maps now? As Sensis are very slow and the last update was about 1 year ago, I normally use and update Tomtoms, so this will be my first attempt at a Garmin, I have read the instructions but will tackle this with caution.