Exhaust modifications are among the most financially efficient and easy ways to get more power from almost any engine. Dollar for dollar, a set of good headers can free up more horsepower and torque than just about any other modification you can perform other than major engine modifications or an all-out engine swap. We had already installed a new totally built high-performance engine, a 408ci small-block Mopar V8 based on a 360ci block in our 1966 Plymouth Barracuda.
The new engine cranked out 586 hp on the engine dyno, so that was checked off our list. We had also upgraded the car with an RMS (PN: RMS306) Alterkation coil-over suspension kit that included a full K-member replacement. When we did start looking for headers, we liked what we had seen working with Doug’s Headers in the past on a 1969 Chevrolet Corvette with a Tri-Power 427ci V8, and especially appreciated the fact that Doug’s offered exhaust manifolds for more than just the usual musclecar.
Our subject, a built 408ci small-block Mopar V8 based on a 360ci block, ready for headers.
Doug’s Headers is one the most respected companies in its industry, and began in 1958 as a small muffler shop in East Los Angeles, California. Growing rapidly due to its ever increasing reputation for high-quality high-performance products, the company has continued to expand and is known for its innovative headers for musclecars as well as dragsters.
We make sure there are as few bends as possible in any header we design. – Don Lindfors
The company makes headers for the ’66 ‘Cuda in its stock configuration with the factory torsion bars in place and the steering column in its original position. Due to the steering box move that was a side-effect of the RMS K-member installation, the column is a tad lower where it passes by the exhaust ports on the head than it is in factory form. The tubes are also arranged in a different pattern as they approach the collectors to clear the factory torsion bars.
It wasn’t until we got to talking with the guys at Doug’s that we discovered it didn’t have what we needed for our 1966 Plymouth Barracuda in its modified state. As a matter of fact, it seemed that at the time, there were no headers available on the market for that car.
The ready to bolt up product now for sale that Doug’s designed on the car, like all Doug’s Headers kits, comes complete with hardware, connectors, and special gaskets.
Our next step, because we wanted to work with Doug’s (and the guys there liked the idea too) was to use our ’66 ‘Cuda to prototype and create a new product (PN: 454) to complement the RMS K-member, and address the new K-member’s manifested alterations to other parts of the car. Prototyping a set of headers isn’t like building something out of Lincoln Logs, it’s just not that easy.
The headers for the 1966 Barracuda took some time, but it also wasn’t like NASA going to the moon. As Don Lindfors put it, “With certain applications, the shape of the car’s body, engine, transmission, and suspension architecture dictate how the headers are designed. With this car, we literally followed the path of least resistance.”
Prototyping the headers involved installing a set of flanges (top left), then using different angles and lengths of tube (top right) to create the perfect fit, while optimizing flow to pull the most power out of the engine. During the design process Doug's makes sure that the tubes work around components such as oil filters (bottom) so they don't need to be removed for installation.
The engineers at Doug’s figured out what lengths and diameters of tubing were required to keep spent gases flowing as quickly and smoothly as possible. Then the pieces were spot-welded in place as they planned out how to create tubes for each cylinder that came as close as possible to the same length. Lindfors told us, “Every place in a header where you have to create a bend slows down the flow of exhaust gases. We make sure there are as few bends as possible in any header we design.”
Once we got the Doug’s headers in our shop and began the installation on the ’66 ‘Cuda, we realized just how important the huge amount of work the company put into the design of the headers really was. We didn’t have to loosen or remove the engine mounts, loosen the K-member, remove the starter, or remove the oil filter. The only thing we had to get out of the way was the steering column, which was unbolted and slid out through its hole in the firewall.
The steering column and shaft (top left) had to be removed prior to installation, and the valve covers were removed (top left) for easy access to the flange mounting bolts. The headers for the '66 'Cuda had to be slung into position (bottom) from the underside of the car.
The removal of the steering column was dictated by its close proximity to the rear-most driver’s side cylinder exhaust port on the head. The header had to be designed to loop above the steering column, because there wasn’t sufficient room to route a header tube under the steering column out of that cylinder’s exhaust port on the head. The other minor issue involved in the installation was that the work had to be done from the bottom side as well as the top side of the car.
After hand-tightening a couple of flange bolts to hold the headers in place, the installation was finalized from the topside of the engine.
There was not enough clearance between the engine and the inner fender well to slide the headers into position from the top. However, it was sure a heck of a lot easier to begin (loosening the bolts on the factory manifold) and end the job (tightening the bolts on the Doug’s Headers exhaust manifold) from the top with all the room upstairs to swing a wrench.
We had it a bit easier than the average home mechanic because we were also able to take advantage of the Bendpak XPR-10ALP lift in the Power Automedia shop by hoisting the car above our heads. We can honestly say, even without the assistance of the lift, that this installation would have been just about the quickest and easiest header swap we have ever performed.
The loop created in the driver’s side header to allow for the close proximity of the steering shaft to the exhaust port on the head can clearly be seen here as the shaft and column are re-installed.
Every Doug’s header comes with all the necessary mounting hardware, collector reducers or connector pipes, premium gaskets, and detailed installation instruction sheets. Construction highlights include machined flanges measuring 3/8-inch thick for greater resistance to warping; CNC mandrel bent tubes for cleaner and quicker flow; and a long tube and long collector design that helps to reduce backpressure, creates more power, and allows higher engine speeds (rpm).
In addition, all of the header tubing is a heavy 16-gauge steel, and the tubes are pre-polished to remove any scratches. You can get the headers in raw steel (ready for custom coatings), Hi-Temp Black coating, or Metallic Ceramic Coating. Doug’s also offers special extra-thick gaskets that are rated up to 1,100 degrees F, pressures up to 3,700 psig (255 bar), and are designed to perfectly match the port with the headers.
One of the things we really liked about the headers designed by Doug’s was the excellent access to the engine’s spark plugs.
Obviously, Doug’s make more than just headers for Barracudas. As a matter of fact, the company’s spread of product offerings includes AMC, Buick, Chevy, Dodge, Ford, Mercury, Olds, Plymouth, and Pontiac. You can find headers for everything from the AMX to the Ventura (that’s Pontiac’s version of the Nova). Doug’s also makes headers for trucks, street rods, and dragsters.
With this car, we literally followed the path of least resistance. – Don Lindfors
Even more impressive than its broad array of product is the craftsmanship with which the company develops new products right on the vehicles they are intended for, and then re-checks them numerous times during the design and manufacturing process to make sure they fit just right. These are not headers designed on paper. Doug’s Headers are designed on the engine in the car for each and every specific application.
If you’re looking for a high-performance aftermarket header for your ride, you can’t go wrong if you make Doug’s Headers a part of your search for parts. For more details, and the full list of applications, Check out the Doug’s Headers website or call (909) 599-5955.
With the valve covers back on, the header installation on the ’66 Barracuda was all buttoned up. Looks pretty sweet, don’t you think?