Here's a similar article from Autoblog;
Autoblog is reporting that the new 6.4 Hemi will produce 480 hp. Here is the article:
First and foremost among the predicted changes on the 2011 Dodge Challenger SRT-8 is more power from an enlarged 6.4-liter Hemi: a bump of 55 horsepower and 40 pound-feet of torque. That would put the big coupe at 480 ponies and 460 lb-ft., and rumor also has it that power will get to the wheels through an eight-speed automatic transmission developed by Chrysler and ZF. Also according to Allpar's inside man, output levels will remain the same on the R/T model, while the base SE will get Pentastar V6 engines with 40 more horses and 20 more lb-ft, for 290 hp and 270 lb-ft. in total.
Most of the other supposed changes seem meant to make life easier for Chrysler and Challenger buyers. The floorpan is being reworked so the car fits more easily into Charger and 300 production, an electric power steering pump is coming onboard and an upgraded interior is in the offing. Cosmetically, the muscle car picks up the Charger's door handles, the Magnum wagon's hatch release button for its trunk, and the lower front grille gets turned upside down.