Hennessey Performance Engineering is in the business of building some pretty wild aftermarket machines, and the latest toy at the Texas tuning company is a Jeep Grand Cherokee Trackhawk

We've previously seen HPE perform some baseline top-speed runs with the Hellcat-powered SUV, but the company has shared video of the HPE1000 package hitting the dyno. The company has claimed 1,012 horsepower at the crank in the past, but a rear-wheel-drive dyno shows that 823 hp makes its way to the rear wheels. The crank figure seems possible, but there'd be a lot of parasitic loss for that to happen.

It's important to note that this is, indeed, a rear-drive dyno—not an all-wheel-drive unit. Hennessey said it's able to disable the AWD system with a few software tweaks. 

When HPE first announced the 1,012-hp upgrade, we immediately questioned how the all-wheel-drive system would handle an extra 305 hp over the stock output. Jeep already modified the full-time active transfer case with forged steel chain sprockets and a wider chain.

With that all said, the horsepower figure is still pretty impressive. A stock Grand Cherokee Trackhawk musters 707 hp from the 6.2-liter supercharged Hellcat V-8 engine, after all. Most of the added gusto from HPE comes from a 4.5-liter supercharger tacked onto the massive engine.

Grab a look at the few pulls in the video above, and also take in the sweet, sweet sounding exhaust note.