Performance Diesel Parts for Cummins: How to Choose the Right Upgrade
Posted by Diesel Power Source on Sep 21, 2026
Search "performance diesel products" and you get a list of parts with no explanation of which ones actually change how your truck drives. On a Cummins, most of the real gain comes from one place: airflow. This guide covers the performance diesel parts that move air through the engine, what each one does, and how to pick the right level for your year, your power target, and how you use the truck.
Diesel Power Source® designs and manufactures these parts in West Jordan, Utah, for 5.9L, 6.7L, 4BT, and ISX15 / X15 Cummins engines, plus Ford and Chevy swap applications.
Why Airflow Is the Starting Point on a Cummins
A diesel makes power by burning fuel. The limit on how much fuel it can burn cleanly and safely is how much air the turbo can push in and how easily the exhaust can get out. Add fuel without adding air and you get black smoke, rising exhaust gas temperature, and a shorter engine life. Add air first and the fuel you already have burns more completely.
That is why the airflow parts below come before fueling changes on almost every build. Two numbers make the point. On a 5.9L, roughly 10 horsepower follows every additional psi of boost. On a 6.7L, it is roughly 13.5 horsepower per psi. Getting the air right is the fastest, most durable way to move those numbers.
The Five Performance Diesel Parts That Change How a Cummins Runs
1. Exhaust Manifold
The factory manifold is the most common restriction on a stock Cummins and the most common failure point on a modified one. Heat cycling warps and cracks cast manifolds, and a warped manifold leaks, which costs you spool and drive pressure.
Diesel Power Source® manifolds are cast in HSMD (High Silicon Molybdenum Ductile iron) and designed with Computational Fluid Dynamics testing rather than copied from the factory casting. The 6.7L T4i manifold flows 72 to 75 percent better than factory. The 5th Gen manifold flows more than 75 percent better. The ISX15 / X15 manifold flows 22 percent better than factory and drops exhaust gas temperature 75 to 100 degrees F on its own.
Shop manifolds: all Cummins exhaust manifolds, 5.9 Cummins manifolds, 6.7 Cummins manifolds, ISX15 / X15 manifolds, 4BT manifolds.
2. Single Turbo Upgrade (S300 and S400 Platform)
A larger single turbo is the direct path from a stock or lightly modified truck to the 450 to 750 horsepower range. Diesel Power Source® single turbos are built on the S300 and S400 platforms and then modified, machined, and balanced in house, so they are DPS turbos on a known platform rather than rebadged units.
The S300 lineup maps to power like this:
| Turbo | RWHP Range | Typical Use |
|---|---|---|
| S362/68/.70 | Stock to 450 | Daily driven, stock to mild fueling |
| S363/68/.70 | 375 to 525 | Towing with added fuel |
| S363/73/.80 | 400 to 575 | Heavier towing, higher sustained load |
| S366/73/.80 | 450 to 650 | Street and strip, larger injectors |
| S369/73/.80 | 500 to 750+ | High horsepower single turbo builds |
Shop singles: S300 single turbos, S400 single turbos.
3. VGT Turbo Upgrade (HE-Series and Turbonator®)
A variable geometry turbo changes its effective turbine size as load changes, so it builds boost early without choking at the top. On 2007.5 and newer 6.7L trucks, the factory HE300VG is already a VGT, which means an upgrade is a direct replacement rather than a conversion.
| Turbo | Compressor Wheel | RWHP Range |
|---|---|---|
| Factory HE300VG | 60mm | Stock to 400 |
| DPS HE363VG | 63mm | Stock to 550 |
| DPS HE366VG | 66mm | 425 to 650 |
The Turbonator® VGT is a separate product line: a variable geometry turbine housing that fits S300 and S400 platform turbos on any 5.9L or 6.7L Cummins from 1988 to 2018. Every version spools the turbo at least 200 engine RPM earlier than the same turbo without it. The electronic actuator version also adds exhaust brake capability. The three stage pneumatic version gives the spool benefit without the brake.
Shop VGT: HE300VG and HE400VG VGT turbos, Turbonator® VGT upgrades. Background reading: What is the Turbonator® VGT.
4. Compound Turbo Kit
Compound turbos are the most misunderstood item on this list. They are not reserved for high horsepower builds. A compound system runs a small turbo and a large turbo in series, which widens the usable RPM range of the engine and splits the load between two turbochargers instead of putting all of it on one.
The practical result is a 200 to 400 degree F drop in exhaust gas temperature. That is the number that matters when you are towing a fifth wheel over a grade in August. Compounds protect the engine rather than stress it, they burn fuel more completely in the cylinder, and when sized correctly they work at any performance level, including stock fueling. Plenty of Diesel Power Source® customers run compounds on stock fuel with no other changes.
Stage pairings for the 6.7L:
| Stage | Pairing | RWHP Range |
|---|---|---|
| Stage 1 | S363 over S475 | 450 to 650 |
| Stage 2 | S363 over S480 | 500 to 700 |
| Stage 3 | S366 over S480 | 550 to 1,000 |
| Stage 4 | S369 over S480 | 600 to 1,200+ |
Stage pairings for the 5.9L:
| Stage | Pairing | RWHP Range |
|---|---|---|
| Stage 1 | S362 over S475 | 400 to 625 |
| Stage 2 | S362 over S480 | 425 to 700 |
| Stage 3 | S363 over S475 | 475 to 750 |
| Stage 4 | S366 over S480 | 600 to 1,000 |
| Stage 5 | S369 over S480 | 700 to 1,200+ |
Most Diesel Power Source® compound kits include a DPS manifold and, on 2010 to 2018 trucks, a patented cast and machined hot pipe that removes the fabrication step other kits leave to you. Diesel Power Source® is also the only manufacturer offering a bolt-on compound kit for the 1st Gen 1988 to 1993 trucks.
Shop compounds: compound turbo kits. Background reading: the complete guide to Cummins compound turbos.
5. Add-A-Turbo Kit
On 2007.5 to 2018 6.7L trucks, the Add-A-Turbo kit keeps the factory manifold and the factory turbo as the high pressure unit and adds an S400 platform atmospheric turbo underneath it. EGR, DPF, and the factory exhaust brake all stay in place, so the kit is emissions compatible and the truck keeps the third stage engine brake.
| Atmospheric Turbo | RWHP Range |
|---|---|
| S475/96/1.32 | Up to 600 |
| S480/96/1.32 | 600 to 700 |
Shop Add-A-Turbo: Add-A-Turbo kits.
How to Choose by Power Target
| Your Goal | Start Here |
|---|---|
| Stock power, lower EGT while towing | Exhaust manifold, then a correctly sized compound kit |
| 400 to 550 RWHP daily driver | Manifold plus an S363 single or an HE363VG on a 6.7L |
| 550 to 700 RWHP tow rig | Compound kit, Stage 2 or Stage 3, or an Add-A-Turbo on a 2007.5 to 2018 6.7L |
| 700 RWHP and up | Compound kit, Stage 4 or Stage 5, with supporting modifications |
| Keep emissions equipment in place | Add-A-Turbo kit on 2007.5 to 2018 6.7L |
| Want exhaust brake capability | Turbonator® VGT with the electronic actuator |
If you are between two options, the Turbo Selector narrows it by year and engine, or call the shop at 801-930-8404.
What Has to Keep Up With the Airflow
More air means more cylinder pressure, and cylinder pressure is what finds the weak link. These thresholds come from the Diesel Power Source® knowledge base and are worth planning around before you order.
| Engine Years | Head Studs Above | Fire Rings or O-Rings Above |
|---|---|---|
| 1988 to 2002 | 45 psi | 55 psi |
| 2003 to 2007 | 55 psi | 65 psi |
| 2007.5 to 2018 | 48 psi | 55 psi |
Beyond head clamping, two more limits apply broadly. The transmission usually needs attention around 400 RWHP. The fuel system usually becomes the limit around 500 to 550 RWHP. Stock connecting rods hold up to roughly 800 RWHP, and aftermarket rods carry that to roughly 1,000 RWHP.
Head studs are always a smart move while the engine is apart, but they are not required below the thresholds above.
Fitment by Engine and Generation
Every kit is built for a specific engine and year range, and Diesel Power Source® needs to know the application at the time of order to get the fitment right. Start at your platform:
- 5.9 12V Cummins 1989-1993
- 5.9 12V Cummins 1994-1998
- 5.9 24V Cummins 1998.5-2002
- 3rd Gen 5.9 Cummins 2003-2007
- 4th Gen 6.7 Cummins 2007.5-2012
- 4th Gen 6.7 Cummins 2013-2018
- 5th Gen 6.7 Cummins 2019-2024
- 4BT Cummins
- Cummins ISX15 / X15 Performance
- Fummins conversion kits and Chummins conversion kits
Turbo and compound kits typically ship with the piping to bolt directly to the stock intercooler, turbo air intake, exhaust intake flange, and exhaust pipe, plus the oil supply and drain tubing and hardware. Most kits include a manifold, the exception being 6.7L Add-A-Turbo kits, which reuse the factory manifold. If the truck has an aftermarket intercooler with larger outlet connections, tell Diesel Power Source® at the time of order so the piping matches. ISX15 / X15 orders require an engine serial number. Verify your ESN with DPS before ordering.
What This Guide Leaves Out, and Why
Generic performance diesel articles usually list fuel pumps, injectors, and cold air intakes alongside turbos, and then promise fuel economy gains. Two things worth saying plainly.
First, Diesel Power Source® builds airflow parts: turbochargers, exhaust manifolds, compound and conversion kits, and the hardware that supports them. Fueling components are a different category and a different conversation, and they belong after the air side is sorted, not before.
Second, Diesel Power Source® does not publish fuel economy claims, because results depend on tuning, load, and how the truck is driven. The numbers published here, exhaust gas temperature reduction, flow improvement, spool improvement, and horsepower ranges, are measured against the factory parts they replace.
Diesel Power Source® also does not sell emissions delete components of any kind. Many DPS turbos and manifolds are emissions compatible, including the 6.7L Add-A-Turbo kit, which retains EGR, DPF, and the factory exhaust brake.
Why Buyers Choose Diesel Power Source®
Diesel Power Source® is a manufacturer, not a reseller. Every air and exhaust product is designed in current 3D CAD, tested with Computational Fluid Dynamics during development to confirm it flows with low turbulence, and machined on current CNC equipment in West Jordan, Utah. That is the reason the flow numbers in this guide exist as measurements rather than marketing.
Kits are designed to bolt on. The cast and machined hot pipe on the compound kits is one example: it removes the custom fabrication step that a lot of compound setups still require. Products are sold under the Diesel Power Source® PMA framework, and coverage varies by product type, so register your product within 14 days of purchase to keep the warranty in place.
Frequently Asked Questions
Do I need a tune before upgrading the turbo?
Not necessarily. A correctly sized turbo or compound kit works at stock fueling, and many customers run compounds with no other changes. Tuning becomes part of the conversation when you start adding fuel to chase a specific horsepower number.
Will a compound kit fit without custom fabrication?
Diesel Power Source® compound kits are designed to bolt on, and on 2010 to 2018 trucks the cast and machined hot pipe replaces the piece most kits leave to a fabricator. Confirm your year and engine at the time of order.
Can I keep my factory exhaust brake?
On 2007.5 to 2018 6.7L trucks, the Add-A-Turbo kit keeps the factory turbo in place, so the third stage engine brake stays. On other setups, the Turbonator® VGT with the electronic actuator adds exhaust brake capability.
Is any of this emissions compatible?
Yes. Many DPS turbos and manifolds are emissions compatible, and the 6.7L Add-A-Turbo kit retains EGR, DPF, and the factory exhaust brake. Diesel Power Source® does not sell emissions delete components.
How do I know which turbo fits my truck?
Start with the Turbo Selector, or call 801-930-8404 with your year, engine, and power goal. ISX15 / X15 customers should have their engine serial number ready.
Where to Start
If the truck is stock and you tow, start with the manifold and a correctly sized compound kit, because exhaust gas temperature is what limits you before horsepower does. If you are chasing a number, pick the stage that brackets your target from the tables above and plan the supporting modifications at the same time. Either way, the fastest path is to confirm fitment first.
Browse all Cummins turbo systems, or read the 6.7 Cummins turbo upgrade guide and what causes high EGT on a 6.7 Cummins for a deeper look. Install documentation for every kit lives on the install instructions and product support page.
Diesel Power Source® designs and manufactures Cummins turbo and exhaust systems in West Jordan, Utah. Free shipping on orders over $350. Cummins is a registered trademark of Cummins Inc. Diesel Power Source® is not affiliated with Cummins Inc.
