Warning above speed limit - change the value

Currently the warning above speed limit kicks in when your are 6 Kms or more over the road limit.

Can this be changed? I would like to reduce it to say only 2 Kms above the limit.

Thanks,

Chris.

It is fixed, otherwise you would have an option for it in the menu.
Also a limit that low would mean you are within the tolerances of what the GPS can do - do you really want to decide between hearing a warning or having someone tailgating you?