This story has been updated. 

Tesla CEO Elon Musk introduced a new "Ludicrous Mode," for the dual motor version of the Model S during a call on Friday. The upgrade costs $10,000 for new buyers and results in a 10 percent acceleration improvement from the previous model. The hold music before the conference call began was a loop of the rap song "Beast Mode" by Ludacris. 

It's a "pretty awesome improvement," Musk said. With acceleration of 1.1 g's, "it's faster than falling."

Tesla will also offer an upgraded battery pack, giving 15 miles of additional range. 

The company was cagey about what it would announce. Reporters were sent an e-mail heads up yesterday, and today Musk said on Twitter that the announcement will be about the Model S: 

https://twitter.com/elonmusk/status/622065785268088834

Musk favors Tweets and secretive press conferences for product announcements, big and small. Tesla watchers are eagerly awaiting news on two upcoming vehicles: the Model X SUV, which Musk today said on track to roll out in the coming months, and the Model 3 mass-production vehicle slated for 2017.

Check back here for more coverage of Tesla's press conference.