The 6.7L Cummins under the hood of a Ram 2500 or 3500 already moves serious air, but the factory exhaust chokes some of that potential with restrictive piping and a heavy muffler. A larger diameter cat-back or turbo-back system lets the turbo spool more freely, drops exhaust gas temperatures on long pulls, and finally gives that big inline-six the deep diesel tone owners actually want. The trick is choosing a system that fits your year and bed length without rattles, and that holds up to road salt and heat cycling.
We compared the most popular 6.7 Cummins exhaust kits sold on Amazon, looking at pipe diameter, material, tip design, sound character, and how cleanly each one bolts up. Whether you run a stock truck and just want better breathing or a deleted setup that needs a full 4 or 5 inch turbo-back, there is a system here for you. Below are our seven top picks, ranked best first.
| Photo | Product | Score | Buy |
|---|---|---|---|
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MBRP S6200409 4-Inch Cat-Back Exhaust Best Overall 4-inch aluminized steel, single side exit, fits 2007.5 to 2018 6.7 Cummins |
9.5 | 🛒 Check Price |
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Flo Pro 4-Inch Stainless Turbo-Back Exhaust Best for Deleted Trucks 4-inch T304 stainless, turbo-back, no muffler, fits 2007.5 to 2018 |
9.3 | 🛒 Check Price |
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aFe Power MACH Force-Xp 49-42342 Cat-Back Best Premium Build 4-inch 409 stainless, dual exit option, polished tips, fits 2007.5 to 2018 |
9.1 | 🛒 Check Price |
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MBRP S6206304 5-Inch Cat-Back Exhaust Best for Big Power 5-inch aluminized steel, single exit, fits high-output tuned 6.7 builds |
8.9 | 🛒 Check Price |
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Flowmaster FlowFX 717878 Cat-Back Exhaust Best Value 4-inch 409 stainless, single side exit, fits 2007.5 to 2018 6.7 Cummins |
8.7 | 🛒 Check Price |
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Banks Power Monster 48995 Exhaust System Best Engineered Flow 4-inch CARB-friendly stainless, single exit, performance-validated design |
8.5 | 🛒 Check Price |
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Magnaflow 17887 Performance Cat-Back Exhaust Best Tone Balance 4-inch stainless, single exit, large polished tip, direct-fit cat-back |
8.2 | 🛒 Check Price |
1. MBRP S6200409 4-Inch Cat-Back Exhaust: Best Overall
The MBRP S6200409 is the system we recommend to most 6.7 Cummins owners because it gets the fundamentals right. The full 4-inch mandrel-bent piping keeps exhaust velocity high without the restriction of the factory necked-down sections, which means the turbo spools quicker off the line and exhaust gas temperatures settle lower on grades. The tone is exactly what diesel owners ask for, a deep purposeful rumble at idle and under load, without the constant cabin drone that ruins long highway trips.
The honest weak point is the aluminized steel construction. It performs identically to stainless on flow and sound, but in the rust belt it will eventually show surface corrosion and weep at the welds years sooner than a stainless system would. If you live where roads are salted hard every winter, budget for the T409 stainless version of this same kit. For everyone else, the fit is genuinely bolt-on, the hangers line up, and it is one of the easiest driveway installs in this class.
- Mandrel-bent 4-inch tubing for smooth, unrestricted flow
- Includes a polished stainless tip for a finished look
- Bolt-on cat-back design with all clamps and hangers
Pros: Excellent flow with a clean, deep tone that is not droney; Trouble-free fit on stock and lightly modified trucks; Strong value for a complete name-brand kit
Cons: Aluminized steel needs care in heavy salt regions
2. Flo Pro 4-Inch Stainless Turbo-Back Exhaust: Best for Deleted Trucks
If your 6.7 Cummins is running a tune and you want the full breathing benefit, a turbo-back system like the Flo Pro is the right call. Replacing everything from the turbo outlet back, the 4-inch T304 stainless tubing removes the restriction the cat-back kits leave in place at the downpipe, so you get the largest measurable flow gain of any setup here. On a deleted, tuned truck that difference shows up as lower drive pressure and cooler EGTs when you are towing heavy.
The trade-off is volume. With the muffler deleted this system is loud, and while it sounds incredible when you stand on it, the constant resonance gets fatiguing on a four-hour interstate run. It is also a bigger job than a cat-back because you are dropping the full system, so plan for a lift or a second set of hands. Note that running deleted is not legal for on-road use in many regions, so make sure this matches how and where you actually drive before buying.
- Full T304 stainless steel for maximum corrosion resistance
- Turbo-back routing replaces the entire downpipe-back system
- Muffler-delete design for the loudest, most aggressive tone
Pros: Premium stainless build resists rust for the long haul; Massive flow improvement for tuned and deleted setups; Aggressive sound that suits a built 6.7
Cons: Loud enough to be tiring on long highway drives; Turbo-back kits are heavier to install solo
3. aFe Power MACH Force-Xp 49-42342 Cat-Back: Best Premium Build
aFe Power built the MACH Force-Xp line for owners who want a flagship cat-back without stepping up to a full custom shop job. The 409 stainless tubing is heavy-walled and clearly more substantial than the aluminized competition, and the mandrel bends hold a true 4-inch path the whole way back. On the truck it delivers a confident, deep tone that stays civil at cruise, which is the balance a lot of daily-driven 6.7 owners are chasing.
Where it loses a half point is value for the visual payoff. The build quality is genuinely excellent, but the polished tips are restrained rather than flashy, so if you are buying partly for show you may feel the premium does not translate into curb appeal the way a brighter dual-tip kit would. As a long-term, rust-resistant breathing upgrade though, this is among the most durable systems on the list, and the fit on Ram 2500 and 3500 trucks is dialed in.
- Heavy-wall 409 stainless construction throughout
- Available dual-exit configuration with large polished tips
- Precision mandrel bends for consistent 4-inch flow path
Pros: Top-tier fit and finish from a respected brand; Stainless build holds up well to weather and heat; Deep tone without excessive cabin drone
Cons: Tips and finish carry a premium feel that some find understated; Heavier than aluminized kits
4. MBRP S6206304 5-Inch Cat-Back Exhaust: Best for Big Power
When a 6.7 Cummins is making serious power on aggressive tuning, a 4-inch system can become the bottleneck, and that is where MBRP’s 5-inch cat-back earns its place. The oversized mandrel-bent tubing gives the most flow headroom of any cat-back we researched, which keeps drive pressure in check on big builds and produces the deepest, most authoritative exhaust note in the group. For a truck that sees the dyno or pulls heavy with a hot tune, the extra inch of diameter is meaningful.
The flip side is that 5 inches is genuinely more than a stock or mildly tuned truck needs, and on a near-factory 6.7 you give up a little low-end exhaust velocity for flow you cannot use yet. Like the 4-inch MBRP, this kit is aluminized steel, so the same long-term rust caveat applies in salty climates. Buy it if your build is already big or headed there, and skip it if you are still running close to stock.
- Full 5-inch tubing for the highest flow ceiling here
- Mandrel bends keep the oversized diameter unrestricted
- Complete kit with tip, clamps and hangers included
Pros: Huge flow headroom for heavily tuned, high-horsepower trucks; Deepest, most authoritative tone of the cat-backs; Still a true bolt-on despite the larger size
Cons: Overkill on a stock or lightly tuned truck; Aluminized steel less rust-resistant than stainless
5. Flowmaster FlowFX 717878 Cat-Back Exhaust: Best Value
Flowmaster’s FlowFX line is the sweet spot for owners who want stainless durability without reaching for the most premium kit on the shelf. The 717878 uses 409 stainless 4-inch tubing, so you get the corrosion resistance that aluminized systems lack while keeping things sensible. The sound is the classic Flowmaster balance, deep and present when you get on the throttle but settled enough at cruise that you will not regret it on a road trip.
The honest limitation is character. Because Flowmaster tunes this system to be broadly agreeable, hardcore owners chasing the most aggressive bark may find it a little tame compared to a muffler-delete or a dedicated performance brand. That same restraint is exactly why it suits a daily-driven work truck so well. For a 6.7 Cummins owner who wants a real stainless upgrade that just works, this is one of the smartest picks in the lineup.
- 409 stainless tubing at an accessible position in the lineup
- Single side-exit with an embossed stainless tip
- Direct-fit cat-back with included hardware
Pros: Stainless construction without the flagship premium; Balanced tone that is loud enough but livable; Straightforward install with good fitment
Cons: Tone is a touch tamer than enthusiast-focused kits
6. Banks Power Monster 48995 Exhaust System: Best Engineered Flow
Banks Power approaches exhaust from an engineering standpoint rather than just selling the loudest pipe, and the Monster system reflects that. The 4-inch T409 stainless design is flow-validated on the dyno, and crucially it is built to keep your emissions hardware in place, which matters for owners who need to pass inspection or simply want to stay street legal. On the truck it frees up the 6.7 noticeably while keeping things buttoned up and refined.
The reason it sits mid-pack here is character and positioning. Because it retains the factory emissions equipment and is tuned for measured performance, the tone is more dignified than the aggressive delete systems, so sound-focused buyers may want something rowdier. It also carries a premium for a cat-back. But if your priority is a properly engineered, durable, inspection-friendly upgrade with data behind it, the Banks Monster is a system you can trust for the long haul.
- Engineered by Banks with dyno-validated flow data
- T409 stainless construction for durability
- Designed to retain emissions equipment for street legality
Pros: Backed by real engineering and flow testing; Keeps the truck emissions-compliant where it matters; Stainless build with strong long-term durability
Cons: More restrained tone than delete-style systems; Premium positioning for a single cat-back
7. Magnaflow 17887 Performance Cat-Back Exhaust: Best Tone Balance
Magnaflow has a long reputation for exhaust that sounds refined rather than obnoxious, and the 17887 brings that to the 6.7 Cummins. The stainless construction and straight-through performance muffler give a smooth, deep note that many owners describe as the most mature-sounding option here. The polished tip looks sharp out the side, and the direct-fit routing makes for a clean install with no fuss on Ram 2500 and 3500 trucks.
What holds it at the back of our list is that the same character making it pleasant also makes it the least dramatic. Owners chasing maximum sound and the biggest flow numbers will find larger 4 and 5 inch systems with delete options give more on both fronts. The Magnaflow trades some of that intensity for refinement and a quality finish. If you want a stainless cat-back that wakes the truck up without shouting about it, this one nails that brief better than anything else here.
- Stainless steel construction with a polished exit tip
- Straight-through performance muffler for smooth flow
- Direct-fit cat-back routing with included clamps
Pros: Refined, deep tone that avoids harsh resonance; Quality stainless build and clean polished tip; Reliable direct-fit installation
Cons: Less aggressive than enthusiasts may expect; Flow gain modest versus larger-diameter kits
Frequently Asked Questions
Will a cat-back exhaust add horsepower to my 6.7 Cummins?
On its own, a cat-back delivers modest horsepower gains on the 6.7 Cummins, usually a handful of horsepower, because the biggest restriction lives upstream at the downpipe and emissions hardware. The real benefits you will feel are quicker turbo spool, lower exhaust gas temperatures when towing, and a much better tone. To unlock larger power numbers you need to pair the exhaust with tuning and intake upgrades, at which point a free-flowing 4 or 5 inch system becomes important so it does not become the new bottleneck.
Should I get a 4-inch or 5-inch exhaust for my 6.7 Cummins?
For a stock, lightly tuned, or daily-driven 6.7 Cummins, a 4-inch system is the right choice and keeps good exhaust velocity for everyday driving. A 5-inch system only makes sense once the truck is making serious power on aggressive tuning, where the extra diameter helps keep drive pressure down. On a near-factory truck, 5 inches is more than the engine can use and you give up a little low-end response, so size the pipe to the build you actually have rather than the one you are imagining.
Is aluminized or stainless steel better for a Cummins exhaust?
Both flow and sound identically, so the difference is purely durability. Aluminized steel performs great and is easier on the wallet, but in regions where roads are heavily salted it will show surface rust and weep at the welds years sooner. Stainless steel, particularly T304 or 409 grades, resists corrosion far longer and is worth it if you live in the rust belt or plan to keep the truck for the long haul. If you are in a dry climate, aluminized is a perfectly sound choice.
Will a new exhaust trigger a check engine light on my 6.7 Cummins?
A standard cat-back that leaves the factory emissions equipment, sensors, and DPF in place will not trigger a check engine light, since it only changes the piping behind those components. The kits that cause codes are turbo-back or muffler-delete systems combined with deleting emissions hardware, which the truck’s computer detects and flags. If staying compliant and code-free matters to you, choose a cat-back or an engineered system like the Banks Monster that is designed to retain your emissions equipment.
How hard is it to install an exhaust on a 6.7 Cummins at home?
A direct-fit cat-back is one of the more approachable driveway jobs and most owners can do it in a couple of hours with basic hand tools, penetrating oil for the factory clamps, and ideally a set of jack stands or ramps. The hangers and clamps come in the kit and the system slides into the factory mounting points. Turbo-back systems are a bigger undertaking because you are dropping the full exhaust including the downpipe, so for those a lift and a second set of hands make the job far easier.
Our Verdict
For the majority of 6.7 Cummins owners, the MBRP S6200409 4-inch cat-back is our top pick, blending strong flow, a deep but livable tone, easy bolt-on fitment, and excellent value in one complete kit. If your truck is tuned and deleted and you want the maximum breathing benefit with stainless durability, the Flo Pro 4-inch turbo-back is the runner up worth stepping up to. Match the diameter and style to how your truck is actually built and how you drive, and any system on this list will wake up that big inline-six.
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