nice detailed response. I would like to add that despite the upgrade there are bugs which will soon be fixed. however, i wonder why you would delay buying the car due to such a minor issue which will be fixed soon In-shaa-Allah as i was assured by a representative of the trackworld.
yes there is a slight hissing sound when the unit is on high volume with nothing on. this is strange and not good.
bottom line, do not let slight bugs in the navigation system delay you from buying a good car. they will fix it soon under warranty for free anyway. use the car and if you like it, get it.
i hope they fix the bugs fast.