I have the factory single din dash bezel without the boston acoustics system.. I'm purchasing a Double din bezel and this head unit (http://www.ebay.com/itm/JVC-KW-NT50HDT-BLUETOOTH-DVD-CD-MP3-GPS-NAVIGATION-NEW-/360384542063?pt=LH_DefaultDomain_0&hash=item53e897b56f) What all do I need to install this and have everything work including GPS? I know I need to get the install kit, but what else will i need? And is the install pretty hard? Thanks!