A message in Virgin Media's Help and Support Forum reads - "As we begin migrating you to your new faster broadband speeds, we're making some changes to our subscriber traffic management (STM) policies to help maintain the quality of broadband service you've come to expect. So we’re reducing the downstream speed reduction on 30Mb and above from 75% to 50% and introducing STM on 50Mb and 100Mb. We'll be publishing the full information on this on Monday at http://www.virginmedia.com/traffic/".
"In addition as part of the speed doubling programme, where you'll receive faster speeds and with the significant additional investment we're making to our network, we'll be trialling a variety of different approaches to traffic management over the coming months to make the system more intelligent and flexible, while ensuring the optimal quality of service. We'll publish more information on this as soon as it's available".
A year ago, an Oppenheimer report mentioned that Virgin Media uses Allot's DPI equipment (here).
See "Traffic Management Changes - April 2nd" - here.