I just bought a 07 Expedition EB and it came with a 2P DVD for Navigation. I saw the newest update it the 8p selling new for $199. I chose to purchase a 6p DVD used off Ebay for $60. Is this a good deal? Am I going to see significant improvements from the 2P to the 6P? How can I find out how better the 6P is going to be for me versue the 2P?