2004.5-2007 Dodge 5.9L Cummins Exhaust Parts

Exhaust on the 2004.5-2007 RAM 5.9L Cummins

Mid-2004 is where this exhaust changed. Starting with the 2004.5 trucks, the factory system is 4-inch with a catalytic converter downstream of the Holset HE351CW turbo. Trucks built in 2003 and early 2004 have a 3.5-inch downpipe and no converter. That catalytic converter is the only exhaust aftertreatment on these trucks: the 24-valve 5.9L never used EGR, and no 5.9L ever carried a particulate filter. Up front, a one-piece cast-iron log manifold collects all six cylinders and feeds the turbo. Behind it, the stock turbine housing is the single biggest restriction in the whole exhaust path, even at stock power. That last point shapes what an exhaust upgrade can and can't do on this Cummins.

What fails and why

The manifold. A long inline-six casting grows and shrinks with every heat cycle, and over the years it cracks. It's very common with age, especially on trucks that see a lot of heat cycles. You usually hear it before you see it: a loud ticking or knocking from the manifold that grows with rpm, a noticeable drop in power, and soot around the crack. Once the manifold warps, the manifold-to-head bolts and the turbo flange become leak points as well. Look for exhaust leak noise, an exhaust smell and soot streaks on the head.

Stock replacement vs. upgrade

For a cracked manifold, the fix is a replacement manifold, and new hardware goes in at the same time. Behind the turbo, the compliant upgrade is a cat-back system. It keeps the factory catalytic converter and changes the sound and flow behind it. Be realistic about gains. Since the turbine housing is the main restriction, a pipe-only change does little for power on a stock truck. Treat a cat-back, muffler or tip as a sound and appearance choice. An exhaust brake is the towing choice: it adds engine braking and keeps your service brakes cooler.

What we carry

Here is what's in this section, sorted by job. For other trucks, start at our main exhaust page.

• Cat-back systems: MBRP Armor Lite and Armor Plus kits in 4-inch and 5-inch, listed for the 2004.5-2007 5.9L.
• Mufflers and resonators: MBRP's MK96116 direct-replacement muffler, Quiet Tone and high-flow mufflers, universal 409 stainless mufflers and diesel resonators.
• Tips and heat wrap: MBRP tips with 4-inch inlets and 4-inch to 8-inch outlets, PPE stainless tips, and Mishimoto tips and heat wrap.
• Exhaust brakes: BD Diesel remote-mount 4-inch brakes, turbo-mount air kits, V-band clamps and a cast turbo exhaust elbow.
• Manifolds and hardware: the ATS Diesel Performance Pulse Flow manifold kit, MAHLE gasket sets and head sets, Dorman manifold bolts, stud kits from Gator Fasteners, Fleece Performance Engineering and Mishimoto, plus BD, PPE and XDP bolt kits.
• Pipe and adapters: MBRP universal exhaust adapters and a Banks Power pipe kit made for Banks exhaust systems.

Fitment notes

Three splits catch people. First, the 2004.5 break: exhaust parts for 2003 and early 2004 trucks (3.5-inch, no converter) do not fit the 2004.5-2007 4-inch system with the converter, so check the build date on any 2004. Second, 2007: the 5.9L and the newer 6.7L were both sold as 2007 models, and exhaust parts follow the engine, not the year. Confirm you have the 5.9L before you order. Third, cab and bed: Regular Cab, Quad Cab and Mega Cab (2006 on), with a short or 8-foot bed, change the tailpipe and over-axle sections, and most cat-backs list the cab and bed they fit. These trucks were sold as Dodge Ram; we file them under RAM. When in doubt, verify by VIN.

Frequently asked questions

How can I tell if my exhaust manifold is cracked?

The sound gives it away. A cracked manifold makes a loud ticking or knocking that grows with rpm, and you'll often see soot at the crack and feel a loss of power. Soot streaks where the manifold meets the head point to leaking bolts or a warped flange. The parts to fix both are in the Manifolds section of this collection.

Will a cat-back add power to a stock 5.9L?

Not much. On these trucks the stock turbine housing is the biggest restriction in the exhaust, and pumping losses are significant even at stock power, so changing the pipe alone gives little gain. Buy a cat-back for sound and appearance, or because you need to replace the pipe behind the converter anyway.

I have a 2007. Which exhaust parts fit?

It depends on the engine, not the model year. Both the 5.9L and the 6.7L Cummins were sold as 2007 models, and the 6.7L has a different exhaust with its own aftertreatment. Everything in this collection is for the 5.9L. Check the engine badge or your VIN before you order, or call the shop and we'll check it with you.

Which BD exhaust brake fits my truck?

BD splits these by year. The remote-mount 4-inch brakes come in a 2003-2005 version and a 2006-2007 version, and the turbo-mount air kits are split 2004.5-2005 and 2006-2007. Match the part to your model year, and on a 2007 confirm the 5.9L first. An exhaust brake adds engine braking when you tow and keeps the service brakes cooler.

Does a cat-back or muffler swap remove the catalytic converter?

No. A cat-back starts behind the converter, so the factory catalyst stays where it is. That is why cat-backs, mufflers and tips are the compliant way to change how this truck sounds. The MBRP cat-backs here are listed for the 2004.5-2007 5.9L.

Not sure what fits? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell.