The Viper is back, now officially the SRT Viper, and it's changed a lot in the two years it's been gone. But it's also stayed the same. For starters, its exterior styling retains the sexy shape of Vipers past, with a low nose, long hood and rounded, flowing roofline to an upturned tail, with each side punctuated by massive side exhausts. This is the most refined Viper shape to date. Underneath is the familiar 8.4L V10, now boasting 640 hp and 600 ft-lb of torque, which drives the rear wheels through a Tremec TR6060 6-speed manual transmission. Driving aids such as launch control and stability control are now standard on the Viper, though both can be switched off. The Viper sits on a new chassis, which SRT claims is 50 percent stiffer than before and the whole package is about 100 pounds lighter than the previous car, thanks to super-formed aluminum on the doors and sills and extensive use of carbon fiber in the body panels. Overall weight distribution is 50/50 front to back, and the whole car rides on coil springs with gas-charged Bilstein dampers and tubular stabilizer bars. Braking is done by 14-inch Brembo disc brakes all around, which necessary to stop this rocket; SRT claims a top speed of 206 mph and 0 to 60 mph in the low 3-second range. Two models are available. The base Viper lacks amenities and is aimed at the enthusiast, and SRT claims it to be "a modernized adaptation of the original." The interior is vastly improved over previous models, with a higher standard of materials as well as fit and finish. Sabelt racing seats are standard, as is seat height adjustability -- a first for the Viper. The Viper GTS features leather seating with power adjustability, cruise control, and a two-mode adjustable suspension with Bilstein DampTronic Select shocks. Both cars feature bi-xenon projector headlights with LED daytime running lights and turn signals, while LED taillights feature at the back. A host of interior colors are available, along with three different audio systems from nine to 18 speakers, and eight different alloy wheels. A number of packages are available for the Viper, including the Track Package, which shaves another 57 pounds by offering two-piece StopTech brake rotors, along with ultra-lightweight wheels multi-spoke wheels, and Pirelli P Zero Corsa tires. The Grand Touring Package adds 3D graphic navigation, Bluetooth hands-free connectivity, satellite and HD radio, a rear backup camera and more.