If you're hunting for slant six exhaust headers, you're likely trying to wake up a motor that's been held back by a restrictive cast-iron log for way too long. The Chrysler Slant Six, affectionately known as the "Leaning Tower of Power," is famous for being damn near indestructible, but it was never exactly a high-performance beast straight from the factory. Most of those old 225, 198, or 170 cubic inch engines spent their lives in Dusters, Darts, or old farm trucks, humming along reliably while breathing through an exhaust manifold that's about as efficient as a straw.
Swapping out that heavy stock manifold for a set of real headers is usually the first "real" mod anyone does to these engines. It's the gateway drug of Slant Six tuning. Once you let the engine actually exhale, the whole personality of the car changes. But, as anyone who has spent time under the hood of a Mopar A-body knows, it isn't always as simple as just bolting something on and driving away.
Why the Stock Manifold Is Holding You Back
The original equipment on most Slant Sixes is a single-outlet cast iron manifold. It's heavy, it retains a ton of heat, and the internal passages are pretty cramped. The biggest issue, though, is how the pulses overlap. In a straight-six engine, the exhaust strokes happen in a specific sequence, and in a log-style manifold, those pulses basically crash into each other. This creates backpressure that keeps the cylinders from fully clearing out the spent gases.
When you install slant six exhaust headers, you're giving each cylinder its own dedicated path for a certain distance. This allows for something called "scavenging." As the exhaust pulse rushes down the header tube, it creates a little vacuum behind it that actually helps pull the exhaust out of the next cylinder in the firing order. It makes the engine much more efficient, which translates to better throttle response and a decent bump in torque right where you feel it in the seat of your pants.
Choosing the Right Style of Headers
You've basically got three main paths when you're looking to upgrade the exhaust on a "leaning tower."
Traditional Long-Tube Headers
These are what most people think of when they hear the word headers. They feature long, individual primary tubes that eventually merge into a single collector. If you're looking for the most horsepower at higher RPMs, long tubes are the way to go. Brands like Clifford Performance have been the gold standard for these for decades with their "6=8" philosophy. They're great for a street-strip build, but they can be a bit of a tight fit in some engine bays, especially if you have power steering or a massive starter.
Dutra Duals
If you've spent any time on the Slant Six forums, you've heard of Doug Dutra. His "Dutra Duals" are a bit of a legend in the community. They aren't traditional thin-walled steel headers; instead, they are high-quality cast iron pieces that replace the front half of the manifold system. You then use a modified rear section or another Dutra casting. They give you the flow of a header with the durability and quietness of cast iron. They won't crack like cheap thin-steel headers often do, and they look almost stock, which is cool if you're going for a "day two" vintage look.
Shorty Headers
Shorties are the middle ground. They offer better flow than the stock log but are much easier to install than long tubes. They don't provide as much of a scavenging effect as the long tubes, but they clear the starter motor and the steering box a lot more easily. For a daily driver where you just want a little more pep and a better sound, shorties are a solid choice.
The Shared Gasket Nightmare
Here is the thing about the Slant Six that catch newbies off guard: the intake and exhaust manifolds share the same studs and the same gasket surface. Because the engine is tilted at a 30-degree angle, everything is tucked on one side. When you pull the exhaust manifold to put on your new slant six exhaust headers, you're essentially loosening the intake manifold too.
This makes getting a good seal a bit of a chore. You have to be incredibly careful with the torque sequence. If the flange on your new headers is a different thickness than the flange on your intake manifold (which it almost certainly will be), the factory triangular washers won't sit flat. You'll often have to grind down the washers or use specialized "step washers" to make sure both the intake and the exhaust are being pressed against the head with equal force. If you don't get this right, you'll end up with a vacuum leak on the intake side, and the car will idle like a bag of rocks.
Let's Talk About the Sound
Let's be honest: part of why we buy slant six exhaust headers is for the noise. A stock Slant Six has a very distinct, almost "sewing machine" type of sound. It's rhythmic and quiet, but not exactly intimidating.
Once you put headers on it, that changes completely. A straight-six has a naturally smooth firing order, and with a good set of headers and a dual exhaust setup, it can sound surprisingly aggressive. It's not the thumping lope of a V8, but more of a high-pitched, mechanical howl as the revs climb. If you run a "split" header (where three cylinders go to one pipe and three go to the other), you get a unique rhythmic cadence that sounds like nothing else on the road.
Installation Tips and Clearance Issues
Before you go bolting things up, there are a few "pro tips" that will save you a massive headache. First, check your starter. The factory starters on older Mopars are huge—often called "the brick." Many long-tube headers won't clear that massive starter. You might need to swap to a modern "mini-starter" from a later model Magnum engine (like from a 90s Dakota). They're smaller, more powerful, and provide the clearance you need for those header primary tubes.
Secondly, heat management is real. Because the headers sit right under the intake manifold and the carburetor, they can cook your fuel. This leads to vapor lock in the summer. It's usually a smart move to wrap your headers or get them ceramic coated. Not only does it keep the engine bay cooler, but it also keeps the exhaust gases hot, which actually helps them move faster through the pipes.
Also, don't forget the "heat riser" function. The stock setup has a flapper valve that directs hot exhaust toward the bottom of the intake manifold to help the car warm up in cold weather. Most headers don't have this. If you live in a cold climate, your car might be a little grumpy for the first five minutes of driving until the intake manifold warms up naturally.
Supporting Mods to Make Headers Worth It
Installing slant six exhaust headers is a great first step, but it works best if you give the engine more air on the intake side too. If you're still running the tiny single-barrel Holley 1920 or Carter BBS carb, you're not going to see the full benefit of the headers. Pairing headers with a two-barrel Super Six intake or a four-barrel Clifford intake is where you really start to see the horsepower climb.
Think of it like a system. If you open up the "out" door but the "in" door is still a tiny crack, you're still limited. But once you get a 350 CFM or 500 CFM carb on there with the headers, that old 225 will actually start to pull hard all the way to 4,500 RPM.
The Bottom Line
Upgrading to slant six exhaust headers is probably the single best thing you can do for the "Leaning Tower of Power." It fixes the biggest bottleneck the engine has and gives it a voice that matches its legendary durability. Yeah, the installation can be a bit finicky with the shared gasket surface and the starter clearance, but the result is worth it.
Whether you go with the classic long tubes for that race-ready look or a set of Dutra Duals for a stealthier, reliable street setup, you're going to love the difference. Your car will feel lighter, sound better, and you'll finally be able to merge onto the highway without checking your calendar first. Just take your time with the washers and the gasket seal, and you'll be good to go.