I've installed mine right on top of the head unit, was a little worried about heat and magnetic issues, should i be concerned? I checked after driving for 30 minutes, not much heat from the unit... gps seems to be accurate... thanks

The magnetism from the GPS antenna won't effect the unit since it has solid state storage, heat shouldn't be a factor either. I noticed that with my installation though that my altitude is off because of the (perceived) delay of going through automotive glass