All years of Vipers have 3.07 gears in them stock. Because of the high torque of the motors, they don't need a lot of gearing to get off the line quickly.
Even when lower gears are put in, it is not common to put in anything lower than 3.55's except on the Gen 1 cars where 3.73's are sometime used. The reason some people put the bigger gears in is just to make 6th gear more usable.
On modified cars, once the horsepower goes over about 600-650RWHP most people people stick with the stock 3.07 rear to reduce tire spin problems in 1st gear.