Hennessey’s upgrades start with a mild package labeled the HPE475. This liberates 457 hp from the SS’s 6.2-liter LS3 V-8 by way of new intakes, headers and high-flow catalytic converter. Hennessey also tweaks the ECU to make sure it all runs smoothly.
Other packages are labeled HPE550, HPE600, HPE650, HPE800 and finally HPE1000. A good mid-range package is the HPE600, which will enable your SS to run the quarter mile in 11.84 seconds with a trap speed of 117 mph. The HPE600 package features a custom supercharger and all the necessary fuel system and ECU modifications to also make it run smoothly.
At the big end of town, Hennessey offers an HPE1000 package, which, you guessed it, offers as much as 1,000 hp. For this level of performance, the stock LS3 makes way for a twin-turbocharged 7.0-liter LSX V-8. The engine features a number of forged internals and can be mated with a six-speed manual. The SS’s six-speed auto with paddle shifters can also be mated with this engine, though it will require a performance build and torque converter upgrade.