The 4 Best 5.9 Cummins 24v Performance Upgrades

The 5.9 Cummins 24v is known for its incredible reliability, but is also well known for its performance potential. While CP3 versions of the engine are going to be the most capable, even the VP44’s can produce some decent power levels with just tuning and a few bolt on modifications.

In this guide we’re going to discuss tuning, exhaust systems, intakes, and turbocharger upgrades as four of the best performance modifications for both CP3 and VP44 5.9 Cummins. Additionally, we’ll cover supporting modifications and more.

5.9 Cummins 24v Performance Upgrades

• ECM and TCM Tuning
• Turbo-back Exhaust
• Cold Air Intake Upgrade
• Turbo Upgrade

It only takes a few mods to transform the 24v Cummins from its OEM specs into a behemoth. In order, we suggest tuning, a turbo-back exhaust, a cold air intake upgrade, and a turbo swap to a larger blower. With these mods, you can make more than 450 wheel-horsepower. Importantly, you will want to make sure you have all supporting mods done by that point, but these engines are ridiculously capable. 

If you would rather consume this content via a video, check out our How to Build a 400+ WHP 5.9 Cummins 24v! (VP44 & CR) video below:

1) ECM Tuning

Hands down, the best 24v Cummins performance upgrade is tuning. Tuning was not an option on the 12-valve Cummins, and it really makes the 24v come to life. With just tuning alone and no other bolt-ons, you can add more than 200 horsepower and torque in minutes. That’s no joke and equates to more than 500 horsepower at the crank on later models. 

Flash tuning is incredibly easy and involves installing software from a handheld tuning device onto your truck through the OBDII port under the dashboard. This software has several “maps” or “tunes,” most of which either increase performance, fuel economy, or towing capacity on the 5.9 Cummins. In addition, if you end up adding more mods, you can maximize and optimize their performance with tuning, too. 

In addition to peak numbers, a 5.9 Cummins tuner will improve the entire power band of the engine. This means you’ll have more horsepower soon and it’ll hold out for longer, and the same with torque. Besides maps that offer high-power numbers, there are also some that are focused on improving gas mileage or towing capacity. This make tuners helpful for a variety of purposes.  

For more in-depth info on tuning, check out our 5.9 Cummins 24v Tuning Guide.

2) Turbo-Back Exhaust System

After tuning you’re going to want to start opening up the exhaust. This will reduce back pressure and improve airflow, helping your 24v Cummins to breathe and exhale much easier. It can also help reduce EGT by allowing for better cooling of the turbo. The exhaust connects directly to the exhaust housing on the turbocharger, and routes all the way back to the mufflers. 

Typically, most 24v Cummins owners will go for either a 4” or 5” turbo-back exhaust. If you plan on staying below 500 horsepower, a 4” pipe will be perfectly fine and will not restrict power. For those looking at going over 500 horsepower, a 5” pipe will be more your size. You can use a larger 5” on a build below 500 horsepower for the extra volume, but you won’t see a ton more power. 

3) Cold Air Intake Upgrades

After opening up the exhaust, a good place to continue is a cold air intake. Previously, we looked at the top options in our 5.9 Cummins cold air intake upgrade guide, so make sure to check out that article for the full breakdown.

Adding an upgraded cold air intake is the best way to increase the flow of air into the turbocharger. The OEM system can become a bottleneck once you start turning up the boost and adding a larger exhaust. Getting something with a larger filter that can suck in more air with less restriction will help the engine breathe better, allowing the turbo to work easier and more efficiently. 

4) Turbo Upgrade

For our final 24v Cummins performance upgrades recommendation, we suggest getting a larger turbo. Besides tuning, a turbo swap will give you the largest horsepower and torque gains. Importantly, you will need to do all supporting mods to swap on a turbo, as well as upgrade the injectors. Depending on the turbo size, you’ll also want either 100 hp or 150 hp injectors to adequately keep up with fuel. 

There are many different turbo options available, and you’ll want to keep in mind what you plan on using the truck for. Typically, if you plan on doing a substantial amount of towing, a turbo upgrade might not be the best option for you. You do not want to sacrifice low-end torque for top-end horsepower, which is what larger turbos will do. If you do plan on towing, you’ll want to stick to a 62mm or below turbo for the best low-end response. Even 62mm is pretty big for towing, but it’s hard to find smaller turbo upgrades for the 24v. 

One of the most popular bigger turbos to upgrade to is the ATS Aurora 3000. This will add significant horsepower over stock while still maintaining a pretty good spool. It has a 62mm compressor wheel and a 58mm inducer for quick response but solid top-end power. 

Ultimately, if you want even more performance you can get an even larger turbo. Many 5.9 Cummins are topping the 500-550 wheel-horsepower mark with a turbo swap, showing these engines are more than capable. 

Supporting Mods

If you plan on installing some performance upgrades, you’ll definitely need a few supporting mods to go with it. First off, if you have a 1998–2004 Cummins with the VP44 fuel pump, you absolutely need a lift pump. The lift pump is a low-pressure fuel pump that supplies fuel to the high-pressure VP44. The stock lift pump is notorious for failing, leaving the VP44 starved for fuel, which leads to it failing and thus engine damage. An aftermarket lift pump will ensure a constant flow of filtered diesel fuel to the VP44, making sure it does not catastrophically fail.

Next up, you want to make sure you have a full set of gauges for you to monitor the health of your engine. You will want gauges for exhaust gas temperature (EGT), boost pressure, and fuel pressure, at a minimum. Your EGT gauge will tell you when the engine is beginning to overheat, and usually you want to keep it below 1,400° except for brief periods. The boost gauge will tell you how much boost pressure the turbo is outputting. This can tell you if you are underboosting (have a leak) or overboosting. 

Finally, the fuel pressure gauge will tell you the health of the VP44. If you start to see fuel pressure plummeting you’ll know the VP44 is going south, indicating you need to lay off the throttle and start figuring out a replacement. 

For those looking at running more than 40 PSI of boost, you’ll want to look into head studs to keep the engine together and prevent head gasket failure. With that being said, if you want to run more than the stock boost levels, you’ll need to upgrade to an aftermarket boost elbow to allow for the wastegate to be adjusted. 

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