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5.9 Cummins Manifolds
5.9 Cummins Exhaust Manifolds | 12-Valve, 24-Valve & Common-Rail (1998–2007)
Diesel Power Source 5.9 Cummins manifolds are built for performance and durability. Thick-wall castings, precision machining, and flow-optimized runners help reduce EGT, improve spool, and solve crack/warp issues common to factory units—ideal for daily driving, towing, and mild performance.
Each high-flow cast manifold is engineered for optimal airflow and a precise fit on 1998–2007 Dodge Ram trucks. Options include direct-fit stock-replacement and performance configurations (T3/T4/T4i) to match your turbo setup and power goals.
Shop by 5.9 engine variant
- 12-Valve (1994–1998): Robust pulse energy for quick lighting with performance or towing turbos.
- 24-Valve VP44 (1998.5–2002): Popular street/tow choice; improved flow lowers drive pressure.
- Common-Rail (2003–2007): Smoother runners and proper collector geometry support clean combustion and response.
What is the purpose of the exhaust manifold
The exhaust manifold collects cylinder pulses and directs them to the turbine. Proper runner sizing and collector design reduce backpressure (drive pressure), improve turbo efficiency, and stabilize temperatures under load.
- Efficient flow: Smooth internal paths reduce turbulence and backpressure for better throttle response and lower EGT.
- Heat expansion control: Three-piece performance designs allow controlled movement during thermal cycling, helping prevent cracks and gasket leaks.
- Customization: Upgrading supports stronger mid-range torque, quicker spool, and consistent towing performance.
How to choose the right 5.9 Cummins manifold
- Keeping the stock turbo: Choose a stock-replacement T3 pattern for direct fit and improved durability.
- Upgrading the turbo: A T4/T4i performance manifold provides more flow and stable boost control for larger S300/S400 frames.
- Towing & heat management: Prioritize thicker castings, flat-machined flanges, and pre-tapped ports for EGT/drive pressure monitoring.
Fitment
Designed for 5.9L Cummins in Ram 2500/3500 (1998–2007). Verify head flange pattern, turbo inlet (T3/T4/T4i), wastegate style, and downpipe alignment per the product page for your model year.
When to replace your manifold
- Ticking/hissing on cold start that lessens warm (leak or crack at divider walls).
- Soot trails near flange edges or gasket surfaces.
- Slower spool or higher EGT after load with no other changes.
- Warped flanges or recurring gasket failures after torque checks.
Install & maintenance tips
- Use new gaskets and quality hardware; follow factory torque sequence in stages on a cold engine.
- Apply high-temp anti-seize to studs/nuts; re-torque after initial heat cycles if specified.
- Confirm turbo face flatness, downpipe alignment, and no pre-turbine leaks.
- Add EGT (and drive pressure, if equipped) monitoring for towing or performance use.
Planning related upgrades? See S300 Single Turbos and Add-A-Turbo Kits. For 6.7L applications, visit the 6.7 Cummins Manifolds page.
5.9L Cummins Exhaust Manifold FAQs
Upgrading the exhaust manifold on a 5.9L Cummins improves exhaust flow to the turbocharger, reduces drive pressure, and helps lower exhaust gas temperatures. Performance manifolds are designed to eliminate cracking issues common with factory units while supporting faster spool, better throttle response, and higher horsepower potential for towing and performance builds.
The best 5.9 Cummins exhaust manifold depends on turbo size, horsepower goals, and how the truck is used. Stock-location manifolds are ideal for daily driving and towing, while T4 and performance manifolds support larger turbos, compound setups, and higher boost levels. Choosing the correct manifold ensures proper turbo fitment, efficient airflow, and long-term reliability.
Yes. A properly designed 5.9 Cummins exhaust manifold reduces exhaust restriction, allowing the turbo to operate more efficiently under load. This results in lower EGTs, more consistent boost, and improved pulling power on long grades, making high-flow manifolds a critical upgrade for towing and heavy-use trucks.
