For this image to really work the data set needs to be much larger, there are only ~44k points on this map, increasing the point radius would not work in the towns/cities as they are too close. In order to use a larger point radius than one pixel I would need to move down to the more detailed Ordnance Survey tiles.

Using the options panel on the left you can change some of the details around.

transparent gif used as packer

Related Content

SVG saved graphs of various sync statistics from this data set plotted using Highcharts javascript charting library is available here.
A calculator to estimate an xDSL lines downstream sync rate from both the lines attenuation or is length is over here.
To see what the image would look like with a larger data set have a look at the Ordnance Survey Code Point Open postcode data plotted on the National Grid here.