Wes Duenkel
October 6, 2010

Choosing the right size headers is important to maximize power, especially when using nitrous. Primary tubes that are too large may prevent the engine from hitting the "sweet spot," and primaries that are too small choke the engine and restrict output.

How much? Don Jackson of Lebanon, Tennessee, wanted to find out. His '79 Mustang Cobra has been raising eyebrows at the region's eighth-mile tracks for some time. It looks harmless-it doesn't have a cowl hood, pizza-cutter front tires, or a gutted interior. Only the drag radials hint at the car's potential. But his nitrous-fed 393ci stroker powers the Cobra to consistent 6.40s in the eighth and embarrassing the competition on a regular basis. The only missing piece was a properly sized exhaust to let his big-inch Windsor breathe.

Nitrous-injected engines require generous exhaust flow. An exhaust system that is properly sized and tuned for a naturally aspirated engine can be on the small side when a lot of nitrous is used.

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But even by naturally aspirated standards, this Mustang's exhaust seemed woefully inadequate. A leftover from its milder days, the '79 exhaled through 1 5/8-inch shorty headers, a 2 1/2-inch off-road X-pipe, and a 2 1/2-inch after-cat. With 393 ci and a 180hp-shot of nitrous, this Fox was long overdue due for better pipes.

With arguably the widest selection of tubing sizes, lengths, and engine applications, Hooker headers was an obvious choice. Jackson's engine builder, Darryl White of Revolutionary Performance and Machine, recommended Hooker PN 6228-1 headers. They feature 2-inch-diameter, 30-inch-long primary tubes; 3 1/2-inch collectors; and Hooker's metallic ceramic thermal barrier coating. FlowTech's 3-inch cross-pipe kit and a few reducers would connect the Hookers to a 2 1/2-inch MAC after-cat since Jackson races his car in full street trim.

The specialists at C&C Performance in Carthage, Tennessee, were eager to help with the installation and dyno work. The husband and wife team of Casey and Capri Lawson run this "little shop that could." Besides Jackson, they have many customer cars that regularly punch above their weight. A visit will usually find Casey under a car on the lift and Capri running the dyno. With several eighth-mile tracks within an hour or two of their shop, their Dynojet 244XC doesn't get much rest-and Capri is just as likely to get dirt under her nails as Casey.

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First, Jackson's Cobra was strapped down for a couple baseline runs. Naturally aspirated, the stroked Windsor made 346 hp and 344 lb-ft to the wheels. Output jumped to 482 hp and 522 lb-ft on nitrous.

The car had barely cooled before it was open season on the exhaust. With the '79 on the lift, the headers and X-pipe were stripped from the Mustang. Hooker's 2-inch by 30-inch primaries and 3.5-inch collectors certainly dwarfed those of the shorty headers, but how much power would they unlock?

To fit the cavernous 2-inch primaries to cylinder heads with a standard exhaust bolt pattern, such as the World Products Windsor Senior heads on our test subject, the Hookers come with adapter plates. For maximum performance, the ports on the plates should be enlarged to match the heads. A few minutes with a die grinder opened up the holes sufficiently.

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The extra clearance offered by the car's QA1 tubular K-member and the Hooker's multi-piece design kept cussing to a minimum while jockeying the headers into position. Only the starter had to come loose for a bit more working room. Once the headers were bolted up, the crew started measuring, cutting, and fitting the Flowtech universal cross-pipe kit. A set of slip-fit Hooker reducers mated the 3.5-inch collectors to the cross-pipe's 3-inch tubing, with another pair of reducers and ball-and-socket adapters completing the 2.5-inch after-cat connection.