Project F Word: Building A Custom F100 Exhaust with Holley

At this point, most of you have seen the Ford Muscle Project F Word pickup begin to take shape. The patina craze stretches across the land of gearheads everywhere. Why? Classic trucks ALWAYS turn heads. They look cool but most were designed to be work vehicles so the problem lies with how they drive. Who wants to be behind the wheel of something with 50-plus-year-old technology when you can have the best of both worlds?

The Project F Word F100 fuses both — and then some. Currently, the ’69 Ford truck sports a third-generation Coyote mill backed by a T-56 Magnum from Silver Sport Transmissions, with power transferring through a bulletproof Strange Engineering 9-inch rearend. Going for something un-trucklike, we wanted F Word to carve corners so it sits on a complete QA1 suspension system tailor-made for curves. A set of Baer big brakes sits behind flow-formed Rocket Racing Attack wheels wrapped in sticky Toyo R888R tires. The exterior will stay the way its owner, and Ford Muscle staffer, Ivan Korda found it, an original rusty, oxidized, and sun-faded blue skin holding up to the patina look.

The first thing bystanders hear is an exhaust note. All heads turn to see and then their eyes stay glued as the vintage metal drives by. That brings us to the point of this upgrade. Our good friends at Holley Performance helped us get the ball rolling for a quality, superb-sounding exhaust system. Holley owns many brands, with Hooker Headers and Flowmaster Exhaust being a couple of the prominent legacy names. Hooker was one of the first companies to design Coyote headers, which endeared themselves to us.

From 2011 forward, each generation has changed, meaning slight redesigns were necessary. Although a very popular third-generation Coyote sits between the frame rails, currently there is no aftermarket bolt-in swap header for F Word. Additionally, the high-performance QA1 suspension system makes exhaust routing a bit more challenging for our specific application.

Header Design

Working with the design engineers at Holley, we determined the Hooker BlackHeart natural finished Gen 1 ’11-’14 Mustang headers seemed to be the way to go. Hooker prides itself on making a quality product and has built a solid reputation with the brand. Each header is hand-welded using 3/8-inch CNC laser-cut flanges, 1-7/8-inch mandrel-bent 18-gauge 304 stainless steel primaries, and a 3-inch diameter outlet tube. This design will help scavenge exhaust gasses from the engine making room for fuel-rich air to enter the combustion chamber. This design also begins the rapid flow of exhaust through the rest of the exhaust tubing. You need some back pressure but not enough to rob power and these headers maximize that potential.

The passenger side fit exceptionally well, needing no modification at all. Initially, the 1969 F100 came from the factory equipped with a compact cam-in-block Ford small-block V8, allowing ample room for everything else in the engine bay. Even with the spacious engine bay, the dual overhead cam 5.0-liter Coyote is wide and swallows up precious space in an engine bay.

Exhaust Fabrication

In order to handle corners as we want, QA1’s complete bolt-in kit was picked for better weight placement, among other things. The kit centers the engine, lowering it slightly, and places the assembly back toward the firewall. While this helps lower the center of gravity, it makes other components harder to workaround. After the driver side’s mock-up, it was clear that things needed to be reworked so that the steering shaft is able to move freely past it.

We tabbed Justin Humphery of Humphery Design Solutions, to help by adjusting and welding the header for a custom fit. Aside from the clearance issue, the steering shaft angle must be straight enough to avoid binding and excessive wear. To do this, Justin cut out the number-six cylinder primary from the header. If you face the front of the truck, it’s the second cylinder from you on your right. Watching Justin work his magic was astonishing, snaking the modified primary with ease. A section needed to be bent toward the cylinder head to clear properly. The handcrafted section of 304 stainless looks like it came that way, plus there’s not a detrimental loss of flow.

From the header collector back, Justin custom-built the entire exhaust system using a combination of a Hooker Headers BlackHeart X-pipe for an ’11-’14 Mustang and Flowmaster’s DIY kit. Although the Flowmaster kit comes with an H-pipe, Ivan wanted a particular sound and opted for the 304 stainless BlackHeart 3-inch X-pipe instead. The exhaust pulse through the X-pipe sounds a little raspier while giving up very little to nothing in power loss.

In order to make a dual-exhaust work with our list of modifications, we needed to make a few more modifications. Instead of the typical “X” design running through the middle of the frame rails, Ivan wanted the entire system shifted to the left. Justin’s clever design extended the driver-side piping section for the header-to-X crossover, then shortened the passenger side, offsetting the X collector. The only thing used from the original X-pipe is the collector; Justin custom-designed and purpose fit everything else himself.

Muffler Design

From there, the rear piping sections needed to be adjusted to work with the new placement. Justin fabricated a piece with a smooth, gradual curve to miss the frame rail while the intermediate pipe flows straight into the muffler. Ivan wanted a moderate exhaust note without being excessively loud, so he chose Flowmaster’s FlowFX mufflers. Constructed out of MIG-welded 409 stainless, one side has an offset 3-inch outlet while the opposing side’s outlet is centered. The interior features a proliferated straight-through core with high-temperature absorbent materials, which produces the deeper, “mellow” sound Ivan craves. The FX is also reversible, allowing a universal fit with many different exhaust designs, like Justin’s.

Detail Work

As you can see in the picture below, both mufflers are positioned on their short edges, hugging the frame rail, which saves space and prepares the offset outlet to turn up and over the Strange Engineering rearend. Humphery Design Solutions mounted the exhaust with anti-vibration inserts to secure it to the center cab mount section, with tabs throughout to couple the dual exhaust together. Ivan has an idea of how he wants to finish the system out, but for now, the exit is located right past the axle. Justin made Humphery Design Solutions logos plates and installed them in critical places on the system to provide functionality with a hint of clever advertising.

V-band connections on each exhaust section from the headers back allow ease of access for maintenance in the future if need be. Flowmaster’s U-Fit kit, made of 409 mandrel-bent stainless steel sections, makes piecing together a custom kit easier thanks to slip-fit connections. The combination of Hooker Headers and Flowmaster products combined with Justin’s knowledge and skill made for the perfect Project F Word exhaust, and we can’t wait to hear it in action. Stay tuned for more updates on the Ford Muscle project truck F Word. 

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