DENVER--( BUSINESS WIRE )-- Comcast, the nation's largest Internet service provider, today announced it is increasing the speeds of two of its most popular XFINITY Internet speed plans, Blast! and Extreme 50, in Colorado for no additional cost. Customers will enjoy faster Internet speeds on multiple devices, allowing them to surf, chat, stream HD movies and TV shows, or game online with double the speed. Also for no additional cost, Comcast is increasing the speed of its widely used Performance plan by more than 30 percent. The change is effective immediately. To activate the new speeds, customers just need to re-start their cable modems.