2003-2004 Dodge 5.9L Cummins Intake Horns

The intake horn on the 2003-2004 Ram 5.9L Cummins

After the air-to-air intercooler, charge air passes through the cast-aluminum horn and into a long, runnerless plenum in the head. The grid heater is sandwiched between the horn and the intake manifold. Diesel Power Products sums up the factory piece plainly: the angular design promotes turbulence and the smaller diameter creates a bottleneck. On a stock 5.9L Cummins the factory intake is relatively efficient, so a horn alone is not a big power part. It earns its keep as fueling goes up.

What fails and why

The horn itself is not a wear item; its restriction is a design limit. On a truck with added fuel, that limit shows up as higher exhaust gas temperature and slower spool. What does wear is the plumbing around it. The intercooler boots that feed the horn are well known for cracking and blowing off, which brings a sudden loss of boost, black smoke and high EGT. And the gasket at the horn tears when the horn comes off, so never plan a horn job without new gaskets.

Stock replacement vs. upgrade

An aftermarket horn uses a larger plenum and smooth radius turns to cut pressure loss, and many add ports for a boost gauge. It is usually installed at the same time as turbo or fuel work, and Diesel Hub recommends upgrading the horn whenever intake work is done on the common-rail Cummins. If you are already pulling the factory horn for a gasket or grid heater job, that is the time to decide. Bundle kits go further by pairing a high-flow horn with intercooler pipe work, so you buy the cold side as one package.

What we carry

Wehrli Custom Fabrication leads this collection with the 3.5 in high-flow intake horn and intercooler pipe kit, the Stage 1 and Stage 2 high-flow intake bundle kits for 2003-2007 5.9L trucks, and a 3.5 in silicone boot and clamp kit. S&B offers the 76-1004 performance intake elbow, and Banks Power has the Monster-Ram intake system for 2003-2007 Cummins trucks. For the gasket work that comes with any horn swap, there are the MAHLE G32749 intake heater grid gasket and the MS19355 intake manifold gasket set. If you are redoing the whole front of the truck, the Mishimoto heavy-duty bundle pairs a radiator, transmission cooler and intercooler for 2003-2007 5.9L trucks. Browse all intakes for related parts.

Fitment notes

Aftermarket horns for 2003-2007 bolt in place of the factory horn above the grid heater. Some kits retain the heater and some relocate it, so check before you order. Make sure the horn you pick leaves access to the air tube, which has to come off for injector or valve-cover service: four 10 mm bolts, the dipstick bolt and a 7/16 band clamp. Most parts here are listed for 2003-2007, which covers your 2003-2004 Dodge Ram 2500 or 3500; universal boot kits are sold by diameter, so measure first. Verify by VIN if you are not sure.

Frequently asked questions

Is an aftermarket intake horn worth it on a stock truck?

On a stock engine the gain is small, because the factory intake is relatively efficient. The factory horn's restriction shows up as higher EGT and slower spool once fueling is added, which is why horns are usually installed with turbo or fuel work. Diesel Hub recommends doing the horn whenever you are doing intake work anyway.

Do I need a new gasket when I swap the horn?

Yes. The gasket at the horn tears on removal, and TDR's advice is to use a heat-resistant gasket and keep spares. Have the MAHLE G32749 or another new gasket in hand before you start.

Will a new horn get in the way of injector work?

It should not, but check. The air tube has to come off for injector or valve-cover service, held by four 10 mm bolts, the dipstick bolt and a 7/16 band clamp. Pick a horn that leaves room to reach them.

Can I run a boost gauge off the new horn?

Many aftermarket horns have ports that make it easy to connect a boost gauge. Check the product listing for port size and location before you order gauge fittings.

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.