The 300c has a 5.7 L Hemi producing 390 ft-lbs of torque.
The 2005 Corvette has a 6.0 L engine producing 400 ft-lbs of torque.
New Pontiac GTO, 5.7 L producing 365 ft-lbs of torque.
If you want a technical explanation of how a hemispherical combustion chamber is better than normal, go here: http://auto.howstuffworks.com/hemi.htm