Was just looking at the older runs compared to the most recent article. The previous run in the other thread was a 2012 with Cup tires.
1:34.4 for a 2012 with Cup tires.
1:33.7 for the 2013 in the most recent test.
So that's only a .7 second improvement if the data in the other thread is accurate between the two cars.
http://www.camaro5.com/forums/showthread.php?t=265930
.7 seconds is a lot. But my guess would be driver, conditions, and continued tweaking of the car. I'd guess there were a few subtle refinements in the 2013 MY. Maybe learned from LeMans racing, maybe from the 427 convertible. Maybe nothing big enough to write home about but enough to make the car a bit better. Could be a simple refinement in the MR shocks. Could be slight improvement in brake pads on those ceramic rotors. Lots of little things could add up to .7 seconds.
Also note in a simple comparison, and these cars are CLOSE, that the Corvette has Carbon Ceraminc brake rotors that are huge compared to the Viper. Now stopping distance may be close (91 to 93 feet) but in the heat of battle, this may simply be enough for the edge.
Also not in the Chrysler response in Twitter "we've run both cars at many tracks and never seen this big a gap". And admission that they have the slower car but just not by that much. Still sounds like they lose on their own comparison.
Just like the Camaros, GM doesn't just sit tight in an off year...........even the last year.