Where is a good place to buy a Zumo 550. Is the 550 a lot different than the 450. I talked to a guy at Daytona last spring and he had the Harley gps system. He was ready to throw it into the ocean, The dealer had it repaired a couple of times and the thing was acting up again. I am using a Magellan now with a ram mount but would like something more weather and vibration proof.