Here is the C&D review "Short Take" I received via e-mail on the 392:

The plastic intake is a two-stage plenum with air flaps that effectively vary the intake ram length based on engine speed. In the block, the camshaft timing is now variable, stretching out the duration of the intake-valve opening for better cylinder filling. (No, it’s not the Viper’s fancy cam-within-a-cam system, so exhaust timing also changes during cam phasing.) The two systems work together to give the 6.4 much greater punch in the 2000-to-4000-rpm range where the 6.1 was somewhat wheezy.

Other engine enhancements include cylinder deactivation on automatic-equipped cars, a fuel-saving feature not offered on the old 6.1, and a rerouted intake [now plastic] that was heavily worked over by computational fluid dynamics software to be straighter and more efficient.

Also, the compression ratio changes from 10.3:1 to 10.9:1. A straighter dual-exhaust system that ends in quad tips “just barely passes” the legal noise-level limit, says McCarthy (Chrysler engineer).

The twin-disc clutch in front of the Tremec TR-6060 six-speed has been changed to accept the greater power, and the pistol-grip shifter’s throws are shorter. The rear differential internals are now shot-peened for extra strength.

Other changes for 2011 include new hydroelastic engine mounts—they suppress idle shake and better control the engine’s mass during cornering—stiffer suspension bushings complemented by larger front and rear anti-roll bars, a steering ratio quickened from 16.1:1 to 14.4:1, and an increase in the front negative camber from 0.8 degree to 1.4 degrees.

We saw a very respectable 0.88 on the skid pad and a clipped 160-foot stopping distance from 70 mph. The tires, Goodyear Eagle F1 Supercars, remain the same summer-tire option as before, with all-season Goodyears also an option.

Inside, the steering wheel is one inch smaller in diameter than the old Challenger’s wheel, and small detail enhancements such as a brushed-metal-look center console make the ambiance less austere.(I believe this is an IE 392 feature only...the IE 392 also has silver color door pulls too)

During some brief track work, the 6.4 roared lustily and pulled the big heavy Challenger up hills and out of corners strongly in third or fourth gear. The 6.4’s power still lives largest closer to the top end, but there’s more excitement in the mid-range than ever before. And now the steering feels much more natural and lively, with a quicker turn-in.
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