The Hennessey Mammoth: The Ram 1500 RHO Monster

Caecey Killian August 29, 2025 2 min read 0

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Boosting the Hurricane Six to TRX Levels

The Ram 1500 lineup has entered a new era with Stellantis replacing its legendary V8 options with the Hurricane twin-turbocharged 3.0-liter inline-six. For purists, the lack of a V8 may sting, but the new Ram 1500 RHO (built on the High Output Hurricane platform) offers plenty of potential. Naturally, Hennessey Performance Engineering wasted no time in extracting even more muscle out of this new powerplant, delivering the Mammoth 700 upgrade.

From 540 HP to a Full 700 HP

In stock form, the Ram RHO’s High Output inline-six produces 540 horsepower, a strong figure for a six-cylinder engine in a full-size truck. But that wasn’t enough for Hennessey. Through a combination of increased boost pressure, custom engine management software, and a stainless steel exhaust system, the tuner has pushed the output to a thundering 700 horsepower.

That’s right on par with the outgoing Ram TRX, which made 702 horsepower from its 6.2-liter supercharged V8. This power increase transforms the RHO into a legitimate high-performance truck while showcasing what Stellantis’ new six-cylinder can achieve with some aftermarket love.

Off-Road Package and Exterior Upgrades

The Mammoth 700 isn’t just about raw horsepower. Hennessey also offers an off-road package that includes a 2-inch suspension lift, leveling kit, and aggressive 37-inch tires on 20-inch wheels. The RHO already rides higher than a standard Ram 1500 with its factory 2-inch lift and 35-inch tires, but the Mammoth setup takes clearance and stance even further.

Visually, the truck gains a new front bumper with an integrated LED light bar, a matching rear bumper, skid plate protection, and Hennessey badging. Performance brake pads and rotors round out the package to ensure the truck stops as well as it goes.

A Bridge Between RHO and TRX

The Mammoth 700 fills an interesting gap in the Ram lineup. While the RHO is the enthusiast’s pick for a factory-built Hurricane-powered truck, many fans still crave the return of a V8. Stellantis CEO Antonio Filosa has already hinted that a revived TRX and other V8 performance trucks are coming, but until then, the Mammoth 700 gives buyers the power, attitude, and exclusivity they want right now.

For enthusiasts who want Hurricane power dialed up to TRX levels, Hennessey’s latest creation ensures the RHO won’t be overshadowed when the V8 does eventually return.

AboutCaecey Killian

Caecey Killian covers builds, installs, and product features for Car Junkie Magazine. He has spent years on the floor of the garage chasing horsepower across SBC, LS, and modern muscle platforms, and that shop time runs through every article he writes. His current CJM project is Project Street Reaper, a 1976 Camaro built around a fresh SBC 350. He is also known for Project Mighty Mouse, a 1977 Chevy Nova running a 1962 small-journal 327 SBC, with build coverage published across multiple online automotive magazines. His media background spans long-form build documentation, install coverage, and product features across the magazine and the Car Junkie Magazine YouTube channel. He writes the way he wrenches: specific, honest about the mistakes, and grounded in real garage work.