I didn't mention the GPS antenna because to me that was a forgone conclusion that it was going to be installed. I did get the antenna and have it installed in the dash. you are correct that is very accurate. I have a garmin Nuvi 660 and the RER works just as good or better than the Garmin. Since I travel a LOT for my job the Nav is a must for me. The garmin is good but I hate having it up on the dash of the Challenger. to me it is almost degrading to the car to have something "stuck" up on the dash....