6.4 a definate improvement in both torque and horsepower. VVT means longer flatter torque curve. More useable power. 6.4 is using the tech from the 5.7. And we know what an improvement that was. Look at the 5.7 2008. Then look what the 5.7 of 2009 does. I think you all will see 475 to 500 out of the 6.4... bank on it.