Really? I love the factory navigation system in my GS. Didn't like the fact that I couldn't use it while driving, but I hacked the system in my 2007 GS350, and put a switch in the 2008 so I could use it while driving, and it's really pretty nice. Bigger screen, more points of interest, more ways to look stuff up, bluetooth w/phonebook, dayplanner, service reminder screen, touch screen for audio controls & climate, faster than Garmin & others, plus, I get the backup camera when I get navigation. That, and I'll get every penny of that navigation cost back in resale because people are starting to really want navigation. So what if I have to get a new map disc every couple years? Also, I've some experience with aftermarket GPS systems (we've had 10 or 12 of them for the other cars), and find that most of the ones with the nicer features are glitchy and unreliable.