2004.5-2007 Dodge 5.9L Cummins Downpipes

The downpipe on the 2004.5-2007 RAM 5.9L Cummins

The 2004.5 update changed this part of the truck. Before it, 2003 and early 2004 trucks had a 3.5-inch downpipe with no catalytic converter. From 2004.5 through 2007, the 5.9L Cummins got a factory 4-inch exhaust with a converter downstream of the Holset HE351CW turbo. So the downpipe on your truck is the piece that ties the turbo into a catalyst-equipped system, and service on it is typically limited to replacing the factory piece or the hardware at the turbo flange.

What fails and why

The turbo end is where trouble shows up. When the cast exhaust manifold warps with age and heat, the turbo flange and the manifold-to-head bolts become common leak points. Signs are exhaust leak noise and smell, plus soot streaks around the joint. If you're chasing a leak near the turbo, check the manifold too, since a warped casting is what turns the flange into a leak point. A cracked manifold makes a loud ticking that grows with rpm.

Stock replacement vs. upgrade

Keep it stock-style. The factory downpipe carries the converter, so the job here is replacement, not redesign. Don't expect power from pipe changes at the turbo outlet either. On these trucks the stock turbine housing is the biggest restriction in the exhaust, and pipe-only changes bring little gain at stock power.

What we carry

This section holds the BD Diesel 1045100 cast turbo exhaust elbow, listed for 2004.5-2007 Cummins trucks. It's the cast piece at the turbo's exhaust outlet. Related hardware lives in this truck's other exhaust sections: the BD V-band clamp under Accessories, and manifold gaskets, studs and bolt kits under Manifolds. For other trucks, see our main exhaust page.

Fitment notes

On a 2004, check the build date: the 3.5-inch, no-converter setup and the 4-inch converter system don't share parts. On a 2007, confirm the engine, because the 5.9L and the 6.7L were both sold as 2007 models and exhaust parts follow the engine, not the year. Verify by VIN if you're unsure.

Frequently asked questions

Is my factory downpipe 3.5-inch or 4-inch?

If your truck is a 2004.5 through 2007 5.9L, it's 4-inch with a catalytic converter. Trucks from 2003 and early 2004 have the 3.5-inch downpipe with no converter. On a 2004, the build date tells you which one you have.

Does replacing the turbo elbow affect the catalytic converter?

No. The BD 1045100 elbow is the piece at the turbo outlet, and the factory converter stays in the 4-inch system. Replacing a damaged factory piece or the flange hardware is normal downpipe service on these trucks.

I hear an exhaust leak near the turbo. Where do I start?

Look at the manifold and the turbo flange. Once the cast manifold warps, the flange and the manifold-to-head bolts are common leak points, and you'll see soot streaks there. A loud tick that grows with rpm points to a cracked manifold. This truck's Manifolds section has the gasket, stud and bolt kits for the fix.

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.