Picking out a 6.7 cummins hood stack kit is usually the point where a build goes from "daily driver" to "full-blown weekend warrior" or dedicated track truck. There is something undeniably aggressive about seeing a massive pipe poking through the hood, ready to scream every time the turbo spools up. It isn't just about looking rowdy at a truck pull, though—there are some actual performance perks and a whole lot of logistical stuff you need to think about before you take an angle grinder to your expensive hood.
If you've been hovering over that "buy" button, you probably already know the vibe. You want that direct exit, the whistle of the VGT (or your big single swap), and the ability to keep your undercarriage clear of soot and heat. But let's break down what actually goes into these kits and what you're signing up for once that hole is cut.
Why Even Run a Hood Stack?
Most people start looking for a 6.7 cummins hood stack kit because they're tired of the traditional exhaust setup. On a 6.7 Cummins, the factory exhaust path is long, winding, and—if you're still running all the emissions gear—incredibly restrictive. Even if you've already gone with a straight pipe, there is still a lot of backpressure created by those several feet of tubing and all those bends over the rear axle.
By moving the exit to the hood, you're giving that exhaust the shortest possible path to the atmosphere. This does wonders for your EGTs (Exhaust Gas Temperatures). When you're pushing a lot of fuel and air, heat is the enemy. Getting those hot gases out within inches of the turbo housing means the engine can breathe much easier.
Plus, there's the clearance factor. If you're into sled pulling or heavy off-roading, you don't want an exhaust pipe hanging low where it can get crushed or hung up on a weight sled. A hood stack tucks everything away, leaving the bottom of the truck clean. And let's be real: the sound is unbeatable. Hearing that 6.7 whistle right in front of the windshield is an experience every diesel fan should have at least once.
What's Usually Inside the Kit?
When you buy a 6.7 cummins hood stack kit, you aren't just getting a piece of pipe. Well, a cheap one might be just that, but a quality kit is a different story. Usually, you're looking at a few key components:
- The Turbo Adapter: This is the most important part. It needs to bolt directly to your turbo's exhaust housing (usually a V-band connection on the 6.7).
- The Transition Pipe: This connects the turbo to the vertical stack. It has to be bent precisely to clear your intake, fuel lines, and wiring.
- The Hood Plate: This is the bezel that sits on top of your hood. It covers up the rough edges of your cut and gives the stack a finished, professional look.
- The Stack Itself: This is the star of the show. You can get them in 5-inch, 6-inch, or even 7-inch diameters, usually finished in polished stainless or a high-temp black coating.
It's worth spending a little extra on a kit that uses high-grade stainless steel. The engine bay of a 6.7 gets incredibly hot, and cheap mild steel will start to rust and look like garbage after just a few heat cycles and a rainy afternoon.
The Part That Makes Everyone Nervous: Cutting the Hood
Let's talk about the elephant in the room. To install a 6.7 cummins hood stack kit, you have to cut a giant hole in your truck. There's no way around it. This is the point of no return.
The best way to handle this is to mount the bottom half of the kit first. Get your turbo adapter and the lower pipe bolted in and secure. Then, you can use a plumb bob or a laser to mark the exact center of where the pipe will hit the underside of the hood.
Don't just start hacking with a Sawzall. Use a template. Most decent kits come with one. You'll want to cut the hole slightly larger than the pipe to account for the engine torquing over. If the fit is too tight, the first time you mash the throttle, the engine will tilt, and your exhaust pipe will try to take your hood with it. A little bit of a gap, covered by a nice hood plate, is the secret to a clean install.
Living With a Hood Stack Daily
Here's where we get into the "real talk" part of the conversation. Driving a truck with a 6.7 cummins hood stack kit isn't exactly like driving a stock Ram 2500.
First off, there's the soot. If your tune isn't perfectly clean, you're going to get a fine layer of black dust on your windshield and your roof. It's just part of the life. You'll find yourself using your windshield wipers a lot more often, and you'll probably be washing the truck every three days if you care about the paint.
Then there's the rain. When the truck is sitting, that big open pipe is basically a funnel for rainwater to go straight into your turbo. You must use a rain cap or a bucket over the stack when you're parked. If you don't, you risk hydrolocking the engine or at the very least, rusting out your turbo bearings. Most guys keep a "stack boot" or a simple chrome flapper on top to handle this.
Lastly, there's the visibility. Depending on where the stack exits, it can create a bit of a blind spot. It's usually not enough to be dangerous, but it takes some getting used to when you're navigating a tight parking lot or a narrow trail.
Performance Gains and Tuning
Does a 6.7 cummins hood stack kit actually add horsepower? On a stock truck, probably not much. You might see a slight drop in EGTs and a tiny bit faster spool-up, but the factory turbo is the bottleneck anyway.
However, if you've upgraded to a larger fixed-geometry turbo or a big S400 frame, the hood stack starts to make a lot of sense. These larger turbos need to move massive amounts of air, and the backpressure from a full exhaust system can actually hold back your peak numbers. In those cases, the hood stack is a legitimate performance mod that helps you squeeze every last bit of power out of your 6.7.
You'll also want to make sure your tuning is adjusted. Since you're removing a lot of backpressure, the way the VGT (Variable Geometry Turbo) behaves might change slightly. A quick update from your tuner can make sure the vanes are positioned correctly to keep your boost levels where they should be.
Is It Right For You?
If you're building a dedicated drag truck or a sled puller, a 6.7 cummins hood stack kit is almost a requirement. It's practical, it looks the part, and it performs. If your truck is a daily driver that you use to take the kids to school or pick up groceries, you might want to think twice. It's loud—like, really loud. The drone inside the cab can be intense since the exhaust exit is only a few feet from your face.
But hey, if you love the sound of a Cummins and you don't mind a little soot on the roof, there is nothing quite like it. It transforms the personality of the truck instantly. Just make sure you measure twice, cut once, and always keep a rain cap in the glovebox. It's one of those mods that tells the world exactly what your truck is built for the second they see you coming.