I just retrofitted oem nav with mini conected on my 2011mcs. I ended up using a GPS antenna from amazon. While testing out the nav to make sure everything is working (for the most part it does) I noticed that every so often when I have a address punched in and it tells me to make a turn. Once I turns it'll either freak out for a sec tell me to make a u turn before fixing itself. Also once I make the turn it'll be "off" it'll show me not on the road for a 1/4 mile then it'll fix itself and show me back on the road. My question is could this just be a map update that needs to be done? (Currently have 2011 maps) could this be a bad nav unit? Or just a not so good gps antenna? I was wanting to use a oem antenna but I wasn't sure if there was any modules between the room mounted antenna and the radio?