Not sure if this would belong to the Off Topic section or general hardware but I'm just wondering if anyone has any experience with 'factory' gps systems. The reason I'm asking is that while I was installing some of my new audio equipment in the car I came across some wiring diagrams for the nav option on Mazda6 and to my suprise the mounting location was beneath/hidden in the dash.

Do they conventionally use external antennas? I havent had a chance to test any 'factory' systems, so I cant say anything about 'lock' times either. Do you guys know if they usually keep it powered all the time to minimize the 'lock' time?

Just curious..