I started out using both portable and unit installed in our Winn '12. Called Winnebago help desk and they sent me to a website www.Naviextras.com/shop/portal and they will guide through update process. You will download update on a cd/dvd. Open the dvd player inside infotainment unit and insert dvd. Helps to copy down the instructions from the website before beginning as it's easy, but not if you skip a step. It's a large download so make sure your not on limited data or you will see your bill shoot up. And yes, we have seen both gps units disagree a bit.