If you're thinking about picking up a hood stack kit for 6.7 cummins, you probably already know that nothing makes a statement quite like a puff of black smoke exiting straight through the bodywork. It's the ultimate "race truck" look, and for a lot of us, it's the natural evolution of a build that's gone past the point of being a simple daily driver. But before you go taking a hole saw to your expensive hood, there's a lot to consider regarding how these kits actually work, what they do for your performance, and the reality of living with one.
Why Even Run a Hood Stack?
Let's be real for a second—most people want a hood stack because it looks incredible. There's no better way to show off a high-horsepower build than by having the exhaust exit just inches away from the turbo. It gives the truck an aggressive, industrial stance that you just can't get with a traditional over-the-axle exhaust. But beyond the aesthetics, there are some genuine performance perks that come with a hood stack kit for 6.7 cummins.
When you eliminate six or seven feet of exhaust piping, you're drastically reducing backpressure. The 6.7 Cummins is a workhorse, but it likes to breathe. By letting those exhaust gases exit immediately, your turbo can often spool up a bit faster. You also lose a significant amount of weight. A full 4-inch or 5-inch exhaust system weighs a lot more than a short piece of pipe and a mounting flange. If you're building a dedicated drag truck or a sled puller, every pound counts, and moving that weight off the chassis is a nice bonus.
Lowering Those EGTs
Another big reason guys switch to a hood stack is to manage Exhaust Gas Temperatures (EGTs). If you've pushed your 6.7 Cummins with a bigger turbo, larger injectors, and some heavy tuning, heat becomes your biggest enemy. A traditional exhaust system has several bends and a lot of surface area that can trap heat under the truck.
With a hood stack kit for 6.7 cummins, the hot air is gone almost instantly. It doesn't have time to linger in the engine bay or travel down the length of the frame. This can be a lifesaver when you're at the end of a hard pull or a wide-open throttle run on the track. Keeping those temps down helps protect your internal components and keeps the engine running more efficiently under extreme stress.
What's Actually in the Kit?
When you buy a hood stack kit for 6.7 cummins, you aren't just getting a piece of pipe. Well, a cheap one might just be a pipe, but a good kit is a bit more involved. Usually, you're looking at a heavy-duty V-band flange that mates up to your turbo's exhaust housing. You'll also get the "stack" itself, which is typically 4, 5, or even 6 inches in diameter depending on how much of a statement you want to make.
The better kits also include a base plate or a trim ring. This is crucial because it covers the jagged edges of the hole you're about to cut in your hood. It gives the whole setup a finished, professional look rather than looking like a backyard hack job. Some kits also come with mounting brackets to ensure the pipe stays rigid. You don't want that stack rattling against your hood every time the Cummins vibrates, which, as we know, is pretty much all the time.
The Scary Part: Cutting the Hood
I won't lie to you—taking a saw to a perfectly good hood is nerve-wracking. It's the "point of no return" for any truck owner. When you install a hood stack kit for 6.7 cummins, you need to be precise. If your hole is off by even half an inch, the stack will look crooked, or it might rub against the metal, causing some nasty vibrations and potentially chipping your paint.
The best way to handle this is to mount the bottom portion of the kit to the turbo first. Then, you can use a plumb bob or a laser level to mark exactly where the center of that pipe hits the underside of the hood. Most guys start with a small pilot hole and then use a template to cut the final shape. It's a "measure five times, cut once" kind of situation. If you're worried about the paint cracking or chipping, using some high-quality masking tape around the cut area can help keep things clean.
The Soot Factor
Here is the part people don't always talk about: the soot. If you're running a hood stack kit for 6.7 cummins on a truck that still sees the street, your windshield is going to get dirty. Every time you get on the throttle, a fine mist of carbon and unburnt diesel is going to waft back toward your glass.
It's not a dealbreaker for most, but it's something you have to live with. You'll find yourself using your windshield wipers a lot more often, and you'll probably want to keep a bottle of glass cleaner in the door pocket. Also, if you have a white or light-colored truck, expect the roof and the hood area behind the stack to get a "patina" of black soot pretty quickly. It's part of the lifestyle, but it's definitely high-maintenance.
Rain and Weather Protection
What happens when it rains? This is a common question for anyone looking at a hood stack kit for 6.7 cummins. Since the exhaust is pointing straight up, it's basically a giant straw for rainwater to go directly into your turbocharger.
Most guys handle this in one of two ways. You can get a classic "rain cap"—the flapper style you see on old tractors. They're functional and have a cool retro vibe, but they can be a bit noisy as they clatter around. The other option is just a simple "stack plug" or even a five-gallon bucket or a coffee can flipped upside down when the truck is parked. If you're driving, the pressure of the exhaust usually keeps the water out, but if you're parked in a downpour without a cover, you're asking for trouble.
Is It Street Legal?
I'm not a lawyer, and every state has different rules, but generally speaking, a hood stack kit for 6.7 cummins isn't exactly "street legal" in the eyes of most DOT officers. It usually involves deleting the emissions equipment, and most jurisdictions have laws about where exhaust can exit (typically behind the passenger compartment).
Then there's the visibility issue. Depending on how tall the stack is and where it's positioned, it can create a bit of a blind spot. If you get pulled over, "it looks cool" probably won't get you out of a ticket. Most guys who run these keep them on dedicated track trucks or live in areas where the local authorities have bigger things to worry about. Just know the risks before you commit to it for a daily driver.
Sound and Vibration
The sound of a 6.7 Cummins through a hood stack is unlike anything else. It is loud. Since the exhaust exit is only a few feet from your ears, you're going to hear every whistle of the turbo and every stroke of the pistons. It's an immersive experience, to say the least.
However, keep in mind that the vibration can be intense. Because the exhaust is often hard-mounted to the turbo and then passes through a hole in the hood, any engine movement is magnified. High-quality kits account for this with proper clearances, but you should still expect a bit more cabin noise and "drone" than you'd get with a full-length exhaust system.
Wrapping It Up
At the end of the day, installing a hood stack kit for 6.7 cummins is about making the truck yours. It's a bold, unapologetic modification that prioritizes performance and attitude over everything else. If you're okay with the extra cleaning, the potential legal headaches, and the stress of cutting your hood, the reward is a truck that stands out in any crowd and sounds like a literal jet engine. It's not for everyone, but for those who want that raw, unfiltered Cummins power, there's nothing better.