$100? Are you kidding me? That cost more than the bypass itself. The installation cost should reflect 1/2 hour to an hour of labor. If the shop is charging $100/hour, they're ripping off their customers. It's easier to install than a car stereo. Auto mechanics charge less than that. Install shop labor is less than repair shop labor. You should not pay more than $50 for the installation. I have installed about 5 of these and I never charged a dime for them. As for sporadic location point. It shouldn't happen while the bypass is on. When you switch on the bypass, the speed drops from whatever your current speed to 0-4km/h. All the bypass that I've installed have the position instantly stopped when the switch turned on. The only time the GPS position acts sporadic is when you turn off the bypass and the nav is updating the current position. The speed resumes then, with the help of GPS antenna, the position gets updated. The position would jump from the position were you initially turned on the bypass to your actual current position instantly, giving you the illusion of sporadic GPS position. It is the same way as the Prestigious society. Prestigious Society Navigation and Video Enhancement Module - YouTube Anyway, as I've said before, you shouldn't be in the map display when you're using the bypass. Also, when the bypass is off, it's a straight connection from the factory harness to the nav unit. I read the problem you're having on http://priuschat.com/forums/prius-v-audio-electronics/104080-entunes-1-8-4-a.html#post1561152 The general vicinity is tracked by the GPS antenna. The forward movement of the vehicle is tracked by the speed pulse on the VSS. The small blue dot you're referring to is the actual position of the vehicle via GPS. I get that sometimes on my nav. It has nothing to do with the nav bypass. My problem that I have once in a while is the nav speed is registering 10X the actual speed when the bypass is off. When I get into the service menu and to the vehicle status, it shows the speed at 500+km/h. This is when the bypass is off. Once I exit out of the service menu, the correct speed resumed and the GPS position is corrected. The bypass didn't cause this. I noticed this behavior shortly after I received the car.