Changes for the 2013 SRT Viper are multitudinous, but also minor, if taken individually. Each and every part of the engine has been massaged and enhanced, sharing almost nothing with the 2010 Viper's statistically identical engine. The sum of the changes, however, is an increase to 640 horsepower instead of 600 (and the engineers think it's underrated at 640), 600 pound-feet of torque, new engine control electronics that enable some shockingly advanced and capable traction control, and, mated to a new closer-ratio gearbox and 3.55 (instead of 3.07) rear-end ratio, truly impressive acceleration at almost any speed.
In fact, the Viper's top speed of 206 mph is now reached in sixth gear, not fifth. And yes, it's only available with a six-speed manual transmission.
That transmission is equipped with a new short-throw shifter that remedies much of the previous Viper's long, heavy throw issues, but which still isn't quite a delight, especially in track driving. Somewhat imprecise and not entirely intuitive, the shift lever's plane isn't perpendicular to the center tunnel, but inclined toward the driver, presumably for ergonomics. If trying to shift while still loaded on the exit of a corner, however, it can be difficult to find third gear at times.
That's not a problem unique to the Viper, however, and it hides a fact about the 2013 model that only those who've experienced the 2010 might realize: yes, you can be on the power while still laterally loaded coming out of a turn. In fact, you can be very hard on the power.
Part of that is due to the re-engineered rear suspension geometry, which relocates the toe links ahead of the spindle and adds some mild compliance (bushing) toe-in in place of the static toe-in and dynamic toe-out. It's also due, in part, to the bespoke tires offered on the Viper. For the track addicts, Pirelli's P Zero Corsa is the choice, providing massive grip, and, with 295/30/18 tires up front and 355/30/19 tires out back, just the right balance between cornering and power application. But part of it is due to the new traction control system.