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3rd Gen 5.9 Cummins | 2003 – 2007

3rd Gen 5.9 Cummins Upgrades (2003–2007)

Reliable power and strong towing performance for the 2003–2007 Dodge/Ram 5.9L Cummins (common-rail). Diesel Power Source turbos, exhaust manifolds, and install hardware improve spool, airflow, and grade control while protecting everyday drivability.

This page highlights third-gen 5.9L fit notes and upgrade paths. If you need 12-valve, 24-valve (’98.5–’02), or 6.7L parts, use the links below. Detailed specs, year breaks, and exact kit contents are listed on each product page.

Why upgrade your 2003–2007 5.9 Cummins

  • Stronger towing & midrange: Flow-optimized manifolds and right-sized chargers help hold speed on grades with lower EGT.
  • Quicker spool: Efficient collectors and clean hot-side routing improve low-rpm response for street and tow manners.
  • Durability: Thick-wall castings with flat-machined flanges resist warping and leaks through repeated heat cycles.
  • Clean fitment: Components modeled around 3rd-gen bay clearances for service access and repeatable installs.

What makes the 2003–2007 5.9L a favorite to modify

The common-rail 5.9L blends strong internals with responsive fueling, so airflow upgrades translate into real-world gains. A high-flow manifold and correctly matched S300/S400 single—or a compound-over-stock path—let you tow steadier, run cooler, and add power without giving up drivability.

Improving fuel efficiency on a 3rd gen 5.9L

Efficiency comes from operating the turbo in its sweet spot. A smoother manifold and properly sized turbo lower drive pressure and help combustion under load. Pair with a healthy intercooler system and proper maintenance to see steadier mileage on highway and tow routes.

How to choose parts for a 3rd gen 5.9

  • Towing & daily: Stock-replacement or T3/T4i performance manifold with a quick-spooling S300-class turbo. Monitor EGT on first towing runs.
  • Street performance: Mid-size S300 or compact S400 with the right turbine A/R to hold speed on grades without excessive lag.
  • Higher-fuel builds: Larger airflow with freer housings and adequate intercooling; plan converter, gearing, and brakes for target power.

Fitment checklist for 2003–2007

  • Confirm T3 vs T4/T4i manifold flange for your turbo choice.
  • Verify downpipe route, intercooler path, and clearance at steering shaft, heater box, and A/C lines.
  • Plan fresh gaskets, quality hardware, heat shielding, and ports if logging EGT or drive pressure.

Install & first-drive notes

  • Use new gaskets and quality hardware; torque in sequence on a cold engine.
  • Pressure-test the charge-air system before first start; check for any pre-turbine leaks.
  • Monitor boost and EGT on shakedown; re-check fasteners after heat cycles if specified.

Shopping related categories? 5.9 Cummins Manifolds (12V, 24V, CR) | S300 Single Turbos | S400 Single Turbos | Add-A-Turbo (Compound-Over-Stock) Kits. For other engines, see 2nd Gen 24V (1998.5–2002) or 6.7 Cummins Manifolds (2007.5–2024).

Dodge Cummins 3rd Gen (2003–2007) FAQs

The 3rd Gen Dodge Cummins includes 2003–2007 Ram 2500 and 3500 trucks equipped with the 5.9L 24-valve Cummins diesel engine.

All 2003–2007 3rd Gen Dodge Ram diesels came with the 5.9L common rail Cummins (24V) engine.

Most 2003–2007 Dodge Cummins trucks came equipped with a Holset HE341 or HE351CW turbocharger, depending on model year and transmission.

Diesel Power Source offers bolt-on and swap-style turbo kits specifically engineered for the 3rd Gen Cummins platform. Product listings clearly identify whether additional components or fabrication are required.

Diesel Power Source specializes in Cummins-specific performance solutions, offering tested turbo systems, manifolds, and kits designed to deliver reliable power and long-term durability for 2003–2007 trucks.

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