[core64]

The factory toyota GPS antenna is mounted behind the HU under the dash. As long as there is no metal above the antenna, it should work fine (plastic, glass, should not affect signal strength). When I installed my factory nav, I did this and it worked fine. I later switched to an eclipse 6610. Eclipse has outside and inside mounting locations. Outside was not a option. Inside was suggested to be on the dashboard (right side near windshield). I opted to put it in the headliner(under the windshield) near the rearview mirror. Was easy to run and almost alway have 4 satellites reception(3 required for gps to work). I dont know how other brands work, but eclipse has a screen that shows satellite reception. One other note, eclipse does include a ferrous metal plate to install under the gps unit. On my location I couldnt use it, but does not seem to be affected.