Sat Nav mods in Brisbane Can anyone help

[Guest001]

Would like to get my Satnav firmware upgraded as it has 2840 in it which is pretty old.

VW wont do it.

Would also like to know 2 other things.

Can the overspeed signal be altered to jump up in 1kph increments instead of 5kph.

Also can electronic speedos be adjusted to be more accurate.

My Passat is just over 3kph fast and the Polo is 7kph fast and is an absolute pain.

I realise they are both legal but coming from a Landcruiser that was spot on at 100kph it drives me mad.

Thanks in advance.