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Horse Sense:
Enforcing it is like shoveling back the tide, but J Bittle has held a trademark on "Shorties," as in shorty headers, since the late '80s. That ought to tell you how long he's been in the mandrel-bent business.
J Bittle has always had a thing for exhaust-the bigger the better. Definitely a child of the Shelby age, the JBA shop has been bending and welding headers together for Fords since the 5.0 was a pup. And, all along, J's been something of a fan of large-tube headers, having offered wonderments such as 151/48-inch equal-length short-tubes (try changing the plugs in your 5.0 with that bag of snakes attached to it) and 171/48-inch long-tubes for racing applications.
Nowadays, modulars are the thing. To keep pace, JBA has worked up a surprising number of mod motor headers and after-cat systems. In JBA lingo, the headers are Cat4ward units, while the after-cat sections are known by the Evol name (because they evolved from the header business, we suppose).
With a minimum of bends-even...
With a minimum of bends-even in 3-inch-diameter tubing-the Evol system for IRS Cobras is still an easy install. Note the short pipes just in front of the mufflers-the intermediate pipes. They are necked down to 211/44 inches to mate with the stock H-pipe. When we tested a prototype 3-inch H-pipe, 3-inch intermediate pipes were substituted to make the system 3 inches all the way. Interestingly, JBA tried X'ing the tailpipes. This mellowed the sound somewhat, but it wouldn't fit in a shipping box, so the idea was abandoned. We don't think you'll miss the X-pipe sound, as the system has a deep, motorboat idle and a stirring, but still polite, fanfare when revved hard.
In true JBA fashion, the Evol after-cat systems are generously sized, as the 3-inch-diameter system for '03 Cobras we're testing here demonstrates. This helps give the system a rich, deep tone, along with providing ample exit room for 6,500 rpm worth of supercharged gasses. Thanks to a blessedly simple exit path, the 3-inch-diameter pipe fits beautifully under the IRS Cobra. As does the stock tubing, the JBA Evol runs nearly straight back from the rear of the stock H-pipe, then has only to make a widely spaced S-curve under the differential and rear suspension before exiting just under the rear valance. This is in marked contrast to live-axle applications, where routing 3-inch pipe up and over the axle proves a daunting packaging puzzle.
As with all JBA's exhaust gear, the company's '03 Cobra Evol is mandrel-bent tubing. The one we put on was mild steel with chrome tips-optional stainless systems are available. The stainless versions also have chrome tips to avoid the yellowing stainless steel takes on once it's been hot. As seen here in mild steel, the Evol after-cat (PN 50-2625) lists for $550, which should translate into $468 or so from the popular mail-order houses.
JBA also offers short- and midlength-tube Cat4ward headers for the newest Cobra. The Shorties are of standard design and typical robust JBA construction, while the midlength Cat4wards are a little different. The idea with those is that a standard, full-length, four-into-one long-tube header on a late-model Cobra often encapsulates the bellhousing sufficiently to require removing the headers before the bellhousing can be taken off. This adds considerable unpleasantness to a clutch job, so JBA lopped off a few inches from the typical long-tube design. This places the header-to-H-pipe mating flange high enough to clear the bellhousing, while still providing enough primary tube length to make a meaningful power increase over a short-tube header.
The pickle is, the better-breathing midlength headers cannot be used with the stock H-pipe, and they have no EO number. That makes them off-road-racing pieces only. The short-tubed Cat4ward pieces do work with the stock H-pipe, have earned smog-legit status with the California Air Resources Board, and thus have an EO number and are legal in all 50 states.
Once available in mild steel, the short-tube Cat4ward headers for the '03 Cobra are now sold only in stainless steel. The full-pop retail price is a staggering $899, while the real-world mail-order price is more like $630. Part of the high price is these stainless headers (PN 1625S-7JT) are also ceramic coated to help with underhood heat and cosmetics. They'll last forever.
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 Hanging the Evol is easy stuff....  Hanging the Evol is easy stuff. The stock system unbolts and removes in one piece. Then you begin at the rear of the Evol and work forward by hanging the tailpipes from the stock hangers. |  Next, the bent tube between...  Next, the bent tube between the muffler and tailpipes is slipped into the tailpipe-it has a bayonet-type hanger (shown here just above JBA technician Eric Anderson's right hand). With this pipe in place, slip on the muffler. |  The last piece is the intermediate...  The last piece is the intermediate pipe between the H-pipe and the muffler. You'll have to push a little to separate the system enough to get the pipe in, but it's no big deal. |