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2003 Ford Mustang Cobra Exhaust Kit - Pipe Scream
Testing JBA's New Cobra Evol After-Cat And Cat4ward Headers On An '03 Cobra
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).
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.
Because we've covered quite a few short-tube, mod-motor header installations, this time we're detailing the Evol system installation while also providing the test results of adding JBA Cat4ward headers, among other things. It's also worth noting that two '03 Cobras were sampled. The main attraction is a stock red convertible a customer brought in for upgraded exhaust; the second is J's personal blue coupe. We're happy to report all parts tested made worthwhile power improvements. Even with the stock H-pipe with stock catalytic converters in place, there is approximately 38 hp to be found with the Cat4ward short-tube headers and Evol system working with stock cats in the stock 211/44-inch H-pipe. That's not too shabby for straightforward bolt-ons.
Speaking of bolt-ons, if you can get the Cat4ward short-tube headers on your Cobra, you won't have any trouble with the Evol after-cat. We've never seen such an easy exhaust system upgrade. It's definitely a driveway job, if that's your thing.
Besides JBA's customer's '03 Cobra, J Bittle put us in his own '03 Cobra coupe for a quick tire smoke and around-the-block evaluation. Souped up with a 2.73-inch blower pulley for a couple more pounds of boost, a set of 131/44-inch primary midlength JBA headers, high-flow cats in a 3-inch H-pipe, and the same 3-inch Evol after-cat system as tested on the red car, J's car proved a rowdy good time.
Naturally, the all-3-inch exhaust system was bound to be heard, and it was. Actually, at idle the exhaust was surprisingly quiet, with a civilized burble rising from under the car like so many bubbles of exotic-car champagne. Get on the pedal, however, and the immediate world was bathed in a sonic discharge heavy enough to announce a serious power contender was at hand, but with the hard edges lightly rounded off. The Flowmaster Delta Flow mufflers receive high marks for their combination of plenty loud but not harsh. They were never "boomy."
While decelerating, the big and open exhaust provided a sporty snap, crackle, and pop as the engine leaned out.
Plenty loud when on the gas normally translates into too loud when using 1,700-2,200 rpm around town-or, with the Cobra's six-speed gearbox, on the freeway. And the cruising results were predictable-an audibly charged cabin perfect for priming the adrenal glands on Saturday night, but definitely overactive for a Tuesday-morning commute.
While inspecting the exhaust with the car on a hoist, we wondered if we'd opt for the big 131/44-inch primary headers. These tubes are so large, not much more than three sheets of paper could be slipped between the starter motor or frame-rails and the header tubing on the passenger side of engine. Given a newer car with fresh engine mounts and not impossibly frozen nuts and bolts, the practicalities of living with such tight clearances seem-well-possible. Indeed, the installation never thunked against floor or driveline, and proved leak-free. But you just know that eventually you'll have to end up working around those monster tubes. We can happily report that the midlength header does easily fulfill its main objective of providing good bellhousing/ clutch clearance, so those chores will not involve header hassles. In addition, JBA also builds these headers with 151/48-inch primaries, which should notably increase wiggle room around the collector.