710 Horsepower Wasn't Enough — So They Built a Monster

Some people buy a Hellcat and call it a day. Our customer isn't one of those people.

This stunning white 2023 Dodge Durango SRT Hellcat rolled into American Muscle Performance's shop as one of the baddest factory SUVs ever built. It left as something else entirely — a fully forged, purpose-built performance machine that Dynojet estimated at a staggering 773.28 horsepower.

That's a gain of over 193 horsepower from a baseline of 580 HP. And that power is real, measured, and calibrated to the last degree.

Here's how it happened.

The Build: American Muscle Performance Goes All In

The team at American Muscle Performance didn't do a mild tune and call it a day. They went deep into this Durango Hellcat's 6.2-liter supercharged HEMI and transformed it from the ground up.

? Engine: Forged 6.2L with CNC Ported Heads & Custom Camshaft

The heart of this build starts with a fully forged 6.2L short block — built to handle the kind of boost and cylinder pressure that would destroy a stock rotating assembly. On top of that foundation, the heads received full CNC porting, maximizing airflow in and out of the combustion chamber for serious power potential.

To complete the valvetrain package, a custom camshaft was selected and installed — dialed in specifically for this combination of heads, displacement, and forced induction. The cam profile works in harmony with every other modification on this build, giving the engine the breathing characteristics needed to produce big, reliable horsepower.

⚡ Supercharger: Ported S/C Snout | 2.85" Upper Pulley | ATI 10% Overdrive Lower Pulley

The factory supercharger got a serious upgrade package:

• Ported Supercharger Snout — removing the restrictions in the inlet path so the blower can breathe and feed the engine the volume of air it demands
• 2.85" Upper Pulley — a smaller upper pulley spins the supercharger faster, generating more boost pressure across the RPM range
• ATI 10% Overdrive Lower Pulley — increases the drive ratio of the entire supercharger system, pushing boost numbers beyond what the factory setup is capable of delivering

Together, this pulley combination dramatically increases rotor speed and boost output — and with the CNC ported heads and custom cam to support it, the engine can actually use that air efficiently.

? Exhaust: Long Tube Headers

To complement the increased airflow from the CNC ported heads and ported supercharger snout, American Muscle Performance installed long tube headers — replacing the restrictive factory exhaust manifolds with a free-flowing design that dramatically reduces back pressure and improves exhaust scavenging.

Long tube headers are one of the most effective exhaust upgrades available for the 6.2L HEMI platform. By allowing spent gases to exit the engine faster and more efficiently, they free up power that the factory manifolds were choking off — and on a build of this caliber, every bit of exhaust flow directly contributes to the final horsepower number.

⛽ Fuel: Upgraded Injectors, Running 93 Octane

With more air comes the need for more fuel. American Muscle Performance installed upgraded injectors sized to match the power level of this build, keeping the air/fuel ratio in the optimal window across the entire RPM range — all on 93 octane pump gas.

No exotic fuel required. Just a properly built and properly tuned engine doing exactly what it was designed to do.

The Baseline: 580 HP Before the Tune

Before N2 Speed touched the calibration, this Durango Hellcat was strapped to the dyno and put down a baseline of 580 horsepower. That number reflects the hardware installed by American Muscle Performance running on the stock PCM calibration — untouched, unoptimized, and leaving serious power on the table.

A well-built engine without a proper tune is like a race engine running on a street map. The parts are there. The potential is there. But without the right calibration, you're never unlocking what the combination is truly capable of.

That's where N2 Speed steps in.

The Tune: N2 Speed Custom On-Site Dyno Calibration with HP Tuners

Our team arrived on-site at American Muscle Performance and got straight to work using HP Tuners — the professional-grade PCM calibration platform trusted by the top tuning shops in the country.

With the Durango strapped to the dyno and HP Tuners connected to the PCM, we began making pull after pull — reading the data, adjusting the calibration, and dialing in every parameter that matters:

• Boost Targeting — commanding the right amount of boost across the RPM range given the 2.85"/ATI pulley combination
• Ignition Timing — advanced to the edge of detonation on 93 octane, extracting every degree of timing the engine could safely support
• Air/Fuel Ratio — dialing in the upgraded injectors for optimal fueling at every load and RPM point
• Throttle Mapping — sharpening throttle response to match the intent of the driver
• Transmission Calibration — optimizing shift points in the TorqueFlite 8HP95 to keep the engine in the heart of its power band
• Drive Mode Optimization — calibrating Sport and Track modes to take full advantage of the upgraded hardware

Pull by pull, the numbers climbed.

The Final Dyno Numbers: Real Results, Real Power

When the last pull was complete, the dyno sheet told the story:

Nearly 200 horsepower gained from a precision-built combination and a data-driven custom calibration. No guessing. No generic maps. Just real power built around this exact vehicle, these exact modifications, and this exact fuel.

This Durango Hellcat now makes more power than most purpose-built race cars — and it's doing it on 93 octane pump gas, in a three-row SUV that can still carry the whole family.

Why Custom Dyno Tuning Matters

A lot of people upgrade their hardware and stop there. They install a pulley kit, swap a cam, port the heads — and then put the car back on the street with either the factory tune or a canned mail-order map.

That's leaving horsepower — and safety — on the table.

Every engine combination is unique. Different atmospheric conditions, different part tolerances, different fuel quality. A custom dyno tune measures the actual behavior of your specific engine and calibrates the PCM to respond to what it's actually seeing — not what a generic tune assumes it should see.

The difference between 580 HP and 773 HP on this Durango isn't just the hardware. It's the calibration that makes the hardware perform.

The Partnership: American Muscle Performance + N2 Speed

This build is a perfect example of what happens when great builders and great tuners work together.

American Muscle Performance brought the hardware expertise — a forged rotating assembly, CNC ported heads, custom camshaft, long tube headers, and a dialed-in supercharger package.

N2 Speed brought the calibration — live, on-site, on the dyno, with HP Tuners, until every last horsepower was accounted for.

The result is a Dodge Durango SRT Hellcat that is faster, safer, and more consistent than anything a canned tune or factory calibration could ever deliver.

Ready to Unlock Your Vehicle's True Potential?

Whether you're building a Hellcat, a diesel truck, a turbocharged import, or anything in between — if your vehicle isn't running a custom dyno tune, you're not getting everything you paid for.

Massive thanks to the team at American Muscle Performance for building this beast. The craftsmanship and attention to detail on this Durango Hellcat is second to none. We love being your tuning partner.