Comcast has doubled the speed of its fastest tier of high-speed Internet service for residential customers in the San Francisco Bay Area, at no additional cost.

The company’s top tier, now called Blast!, will operate at a maximum of 16 Mbps.

Subscribers to the current top tier, Performance Plus, will get an automatic upgrade from 8 Mbps to 16 Mbps on Feb. 22.

Comcast's PowerBoost speed enhancer – which allocates additional bandwidth, when available, to accelerate large file transfers – will continue to apply to the 16 Mbps tier.

The move is an intermediary step to Comcast’s eventual rollout of DOCSIS 3.0 service later this year.

Comcast said it expects to initially offer rates of up to 100 Mbps through the next two years, then upgrade to a version of DOCSIS 3.0 technology that will enable transfer rates up to 160 Mbps.

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