Serious HP used an HP Tuner 2.5 to reflash the Hellcat's ECU. The dyno results? 706 HP and 630 lb/ft of torque at the rear wheels and 830 crank hp!! Watch This Dodge Challenger Hellcat Put Down 706HP...At the Wheels - Boldride.com
668 at the wheels stock. 707hp at the crank? I think that might be slightly understated by Dodge. That only accounts for like 5+% drivetrain loss. Not buyin it.