Hennessey Performance sent us a surprise for the holidays with this 2013 Jeep Grand Cherokee SRT8 package. Under the hood is a Hennessey HPE800 Twin Turbo engine kit that was hooked up to the bored out factory 6.4-liter HEMI V8. Displacement is now at 7.0-liters, allowing the large twin turbochargers to put down 805 horsepower and 823 lb-ft of torque. A huge increase from the stock 465 hp and 465 lb-ft of torque. At the track, the modified Jeep Grand Cherokee now sprints from 0 to 60 mph in just 3.1 seconds, which is damn good for a full-size SUV.