Lee Glaser's '91 LX packed a potent 347 between the front fenders, buthad a 100,000-mile stock 'Stang exhaust down below that begged thequestion, "Why is this here?" Extreme Automotive's Saul "The Surgeon"Gutierrez removes the big gas restrictor and makes way for Flowmaster'sDelta Force 3-inch system.
The burble of Flowmaster mufflers has been common to late-model Mustangsdamn near since the beginning of the 5.0 revolution. Yep--it's been thatlong since we first heard "that sound" on the streets and at dragstripsfrom coast to coast. If you're a true-blue Ford fanatic like we are,knowing the sound of a 'Stang sporting a set of Flowmaster cans comesalmost as easily as remembering your name.
We've often detailed the virtues of a free-flowing exhaust system forany Pony--from pushrod Foxes to new, modular S197s. A larger,unrestricted pathway for exhaust gasses to exit not only improves a'Stang's overall performance (power, torque, and acceleration), but thesight of 2 1/2-inch tips peeking from the back end also looks cool. Inone way or another, larger pipes give the Camaro jockey something tothink about before he tries you at the next stoplight.
Flowmaster has taken the big-exhaust concept a step further with DeltaForce--a new, 3-inch, off-road exhaust system [PN 17389 (LX), $1,053.30;and PN 17396 (GT), $979.07] for '86-'93 EFI Fox Mustangs. When we say"3-inch," we mean the entire system is comprised of 3-inch-diametertubing, from the header collectors all the way back to the tips.Everything's big. And at first look, you catch yourself wondering, Willthis stuff even fit on a Fox? While it definitely has the appearance ofa race exhaust system (the cat-less X-pipe is the telltale giveaway),Delta Force fits like a glove under '86-'93 Mustangs, and itssurprisingly sedate tone--signature Flowmaster, just like the olddays--leads you to believe that performance on the street may have beenthe objective when Flowmaster engineers developed the Delta Force 3-inchdeal.
Removing these modified Flowtech Warlock mufflers couldn't happen soonenough. Electric-solenoid-activated turnout valves were incorporatedinto the mufflers in an effort to improve exhaust flow. We give the ideaa little merit, but the stock cats still restricted flow.
Editor Turner expressed his concern about the type of Mustang we coulduse for installing the big exhaust setup, as logic would lead one tothink a perfect candidate would have a moderately modified 302 or atmost a 347 stroker, but not necessarily already equipped with a mondoexhaust system. Our good buddy, Sal Ybarra, found us the candidate toend all candidates. Sal is the San Fernando Valley 'Stang nut whostarted the widely popular Mustang Drag Days race series at LA CountyRaceway, and a walking, talking database of local Ponys of all flavors.
Lee Glaser, of San Fernando, California, is a budding tractor-traileroperator who owns a 347-powered '91 LX that sported a sinfully anemicexhaust system. Despite having port-matched Twisted Wedge heads andEdelbrock Performer 5.0 intake (the old-school manifold--not today'sPerformer 5.0 RPM II), a hot camshaft, 15/8 short-tube headers, and justabout every other engine and drivetrain goodie that usually makes for acool street ride, we were nearly brought to tears when we looked underthe car. His exhaust consisted of the factory H-pipe (and its four,restrictive catalytic converters), 21/4-inch tubing from front to back,and a muffler setup that was theoretically "cool" but junk functionally.While we didn't know how well Delta Force would work, we did know the3-inch exhaust system would be a marked improvement over the originalparts, and probably would produce the kind of exhaust flow Lee's stroked'Stang really needs.
Flowmaster's Delta Force 3-inch exhaust system for beyond-stock Fox'Stangs made a good impression on us and, more importantly, on the ownerof our test Mustang. Keep reading to see how the simple install was.
This is the Flowmaster Delta Force 3-inch exhaust system for EFI MustangGTs (PN 17396; $979.07). This bolt-on, slip-together, off-road system iscomplete--from the back of the stock or aftermarket short-tube headersall the way to the tailpipe--with mandrel-bent tubing, air-injector smogtube and O2 sensor provisions, Scavenger X-pipe, Super 40 Seriesmufflers, stainless tips, and heavy-duty clamps and hangers. |  | 
Due to the length of the air-injector receiver tube on the X-pipe(longer than the tube on the factory cat pipe), Saul cut down the OEMair-injector pipe a bit. After that, it fit perfectly and was leak free. |
Flowmaster's Super 40 Series mufflers are huge and flow well, butthey're surprisingly less noisy than we thought they would be. Lee's carnow sounds like any other 5.0 with Flowmasters at idle, and thefamiliar, bubbling tone (not head-rattling deep) can also be heard undermoderate and hard acceleration. Note how the 3-inch tubing is nicelybent and clears the axle with ease. Heavy-duty hangers are included withthe kit and mount right in the stock locations, so there's no need to doanything crazy to make it fit. |  |  |