ROUSH Stage III Mustang Cactus Jack’s Prescription For Attack - Hot Rod Magazine

Even though Jack Roush might not have attended every detail of his latest Mustang iterations, you can be quite sure that all the bugs in them were eaten before these cars were offered to the public.  He poured about $7 million of R&D into the current crop, testing the prototypes in Mexico City, Death Valley, Colorado, and other torture venues before he signed off on them.  Cactus Jack doesn’t like to repeat himself, so he gets it right the first time regardless of how much time it might consume.  He stakes his reputation on that.


Obviously, Roush competes with several Mustang tuners.  His version is the only one we’ve gotten our hands on so far, so we won’t be able to compare it outright with something from the halls of a Saleen, Kenny Brown, or Steeda.  Our reference springs from the trials we’ve had with our recalcitrant ’97 project Mustang, a sometimes frustrating experience, especially when rearranging the horsepower and torque curves of the 215hp engine.

All Roush Performance Stage IIIs are based on the current SOHC 4.6L GT, which is factory rated at 260 hp at 5,250 rpm and 302 lb-ft of torque at 4,000 rpm.  In stock form, the GT coupe distributes approximately 3,250 pounds from front to rear in a 45/55 percent spread, a natural hedge against uninvited oversteer, and sometimes alluded to in terms of neutral handling (50/50 actual).  Add the proper size anti-sway bars (always bigger in front) and keep the lawyers happy.  A neutral car is easier for inexperienced hands to drive faster because it is so forgiving.  So despite its healthy engine, you’ve got to be really stupid (or deliberate) with the Stage III to get it going crazy.

Though the engine bay is a lot roomier than the one in the first-gen SN95 (you can actually see and touch the exhaust manifolds from above), doing anything major to the top of the engine is still cause for pulling the engine cradle and suspension from the bottom of the car.  The plan for Roush’s engine is identical to ours: Load on the SVO cylinder heads, attach the SVO shorty tube headers, and put that supercharger right there in plain sight where it says something.  The liquid-to-air intercooler is all but hidden in front of the engine in a very clean, factory-like package.  In a program similar to ours, full boost (6 psi) hits the engine at 2,250 rpm, rolls out the best torque (345 lb-ft) at 3,750 rpm, and stays strong all the way to six grand.

Aside from a Roush high-flow air intake and 8.5mm ignition wires, the 281ci engine is bone stock right down to the 9.4:1 compression ratio.  Changes to the otherwise stock drivetrain include 3.55:1 ring-and-pinion (3.27:1 stock) on a Trac-Loc differential, a beefed clutch, and a 20-pound aluminum flywheel.  Ours has 3.73s and a Centerforce Dual-Friction clutch zinging on the original 30-pound iron flywheel.  Theirs makes 315 hp at the wheels; ours has seen 314.  The performance figures are also quite similar.

Roush Mustang RP13 (a 2000 model) is a warhorse with more than 28,000 miles on the clock.  It didn’t make a peep.  No squeaky joints or anything else to reveal the misery it has endured.  The Roush guys refer to it as "the thing that won’t die." Our car also has 28,000 on it, but it’s three years older than Jack’s.  The suspension on RP13 rides better than the stuff on ours because the Roush guys developed them along with the 18-inch rim and tire package.  Expensive Roush/Alcon four-piston mono-block (billet) calipers on 14-inch discs collaborate with 13-inchers at the rear.  Our car balances 13-inch Baers with 11-inch stockers.  Both setups provide demonstratively better braking.


Aside from the pretty metal pedals (dead pedal included) and the sexy black-on-white instruments, the Stage III is pretty much GT on the inside: plain, functional, and easy to heel-and-toe.  The leather covered seats with the adjustable bolsters and lumbar support are a tremendous improvement over the earlier configurations, like rats in our own Mustang.  The foam rubber padding on the left-side thigh bolster in our driver seat is disintegrating as you read this.  Blame it on the LA ozone… or shoddy parts.  The point is that our seats really suck, and the ones in the Roush are right on the money, affording comfort and lateral support in equal measures.  Auxiliary gauges for fuel pressure and positive manifold pressure cling to the A-pillar at eye level but are not intrusive.

At first, rearward vision seems compromised by the arc of the deck wing, and can be confusing on the night road, but after a short stint, the spoiler becomes invisible.  Unlike the prominent but benign exhaust note coming from the back of our car, you can’t hear the side pipes on Roush Mustang at cruising speed unless you stab the loud pedal.  The three-chamber side exhaust has a warble all its own.

The stock GT is fun to drive and be in.  The Roush version simply plays on these strengths and, in most cases, makes them even better, hugging the belief that a driver who feels comfortable and secure will be more alert and less apt to make errors in judgement.

Ride & Handling

The Mustang provides an excellent platform for more powerful handling.  Roush’s enhancements satisfy functional as well as aesthetic needs.  Unless you’re tooling a Silver Cloud, your car will usually look better with a lower stance.  This concedes ride quality to a degree, so any more than an inch in a strut-suspension car will likely require adjustable camber plates to maintain the correct steering geometry.  The ride could be good, acceptable, or poor, depending on spring rate, shock valving, and the quality of the components.  We think the Roush car would probably handle just as well at stock ride height because its tires are massive and provide excellent grip without having to lower the car’s center of gravity.

At speeds below 70, you aim at the apex of the turn and the car goes there obediently, but meanwhile the steering input feels too little for the speed you’re at and the tires don’t make a sound.  Only when you really tighten up the rack will the front tires begin to protest a tiny bit; otherwise, this is one of the flattest street rides you’ll ever be in.  We purposely tried to upset the car by avoiding the (Mustang freak) HRTV cameraman at the very last sliver of time so he could record the red car’s dynamic abilities as it passed in front of him.  The director (also a Mustang freak and a man stingy with praise) was astounded at how flat the car cornered.  It feels the same inside the car.  Stiff shock valving puts the ride right on the brink of edginess, but the springs temper wheel movement to where the wave is nearly fluid and almost enjoyable.

Depending on speed, certain humps in the road make you lurch violently in the three-point belt.  You’d bang your noggin on the roof of the car were seatbelts not in place.  In two words, the Roush Mustang has a big shouldered feel to it like an SS Camaro or C4 Corvette.

The minimal (35-series) sidewall section has a great deal to do with the "springiness" of the ride.  Considering the 18-inch rubber, and painfully aware of what our Mustang rides like, the Roush suspension crew has massaged a very firm ride into a fluid control most of the time.  The 18-inch Roush rims on this car were 9 inches wide and carried 265/35 and 295/35 BFG Comp T/A tires.  The Roush PR man told us: "We couldn’t get the latest g-Force KDs in time for this test; they are the standard Stage III tires." We admire the 40-series KDs on our Mustang for the prodigious grip as well as their quietness and amiable ride.

Though the leading edge of the front air dam is higher than a standard parking curb, the rest of the undercarriage is invited to scrape over speed bumps regardless of approach angle, a rude minus for the lowered suspension.


When we were coming up in the early ’60s, how well the brakes worked was the last thing on our minds.  We wanted to go straight to Hell and didn’t
care about stopping along the way.  Besides, big drums were all you could get; disc brakes were only on expensive imports.  These days, brakes are just as powerful as the chassis and the drivetrain, and maybe just as expensive.  You don’t think the discs on the Stage III are large? Check out how they gag the inside of those big wheels and become the filling that brings the entire side view of the car together as a whole. Pedal feel is firm, yet accommodating and pliable to the toe.  The braided steel lines make it feel that way and set you up for some of the best braking thrills you’ve ever had.  The massive system is so linear that it seems to neither have nor require a power assist.  This huge swept area is large enough to eliminate the need for an anti-lock feature, as it engages only in the last few feet of an aggravated stopping exercise.

Despite a too-happy foot on the initial decel, the brakes dissipate the energy quickly and evenly.  Because the mono-block front calipers are made of a single piece of aluminum, there are no joints or surfaces to change shape, deflect, or shift under hammer-blow pressure and blast furnace heat, thus clamping ability stays uniform and the car stops like it’s on a clothesline.  When these fiery horror energy-grinders are combined with all that rubber surface area on the tarmac, it tends to make Mustang freaks lurking close by remark that there’s "no doubt about it, the brakes are the best thing about the car.  Sensational!" Remember that they’re Mustang freaks.  Minimal pedal pressure at high speed (120 mph) sucks the car down matter of factly without lurch or drama.  Nice to have friends you can depend on.


The engine in our Mustang began with 45 hp less than one in the Roush car, yet it produces nearly identical output.  Because RP13 is a street-driven automobile, we are more interested in superb driveability than raw power.  To help its aluminum flywheel maintain momentum when the clutch is engaged, the idle speed is 750 rpm rather than 550.  We stalled the engine a few times before we got used to this quirk, but it’s worth the wait when you play mountain-road roulette because it really keeps the revs up on the sweepers.

In a galaxy of taillights and sweltering hostility, the red car behaved like a stocker.  Clutch pedal pressure is light, the grab is smooth, and it feels the same after doing it 100 times in 10 minutes.  Better yet, you can wildly abuse this item like a fever on one day and treat kindly the next and it comes back for more.

A 3.77:1 Low gear snaps the ’Stang off the line, and just where the stock engine begins to wheeze, the supercharger is stuffing the big-valve cylinder heads with lots of go-pressure.  We hit the 6,000-rpm rev-limiter more than once.  Once in Third gear, manifold pressure begins to strut and, real quick, that sucker alongside you is way behind you.  The application of grunt is extremely linear, so the car feels like its being pulled by a magnet rather than shot out of a gun.  You don’t haze the tires going into Fourth gear, either, because you’ll be too busy booking down the road.  Our version feels exactly the same, although to a different blower whine.  It’ll break the tires way loose in Low and Second, but that’s probably a function of the heavier flywheel, stiffer gears, and smaller tires (275/40ZR17).

Smoothness of delivery is the key here, and the heads that hacked the computer deserve frosty beers for life.  Understand that they introduced or changed more than 7,000 codes to include every operating parameter.  Know that most production cars have at least 7,000 codes in the idle system alone.  Whatever the pretzel comparison, the Roush car is more thought out than ours is.  His systems are engineered to fit the whole, not some gaggle of unrelated components trying to make nice to one another when you’re not looking.  All Roush’s ministrations are warranted by Ford.

What It Is

So it’s the package that makes the Roush Stage III Mustang, parts that enhance mechanical goodness as well as delight the eye of the beholder.  This Mustang is nice eye candy.  Not overdone on the cladding, jackboot kinda wheels, and all one color.  At roughly $50,000, it ain’t cheap, but if you want the affiliation and perhaps the collectibility, then it might be.
This article was written by Ro McGonegal.

About the author

ROUSH Performance
ROUSH Performance
ROUSH Performance, a division of Roush Enterprises, designs, engineers and manufactures completely assembled pre-titled vehicles, aftermarket performance parts, and superchargers for the global performance enthusiast market. Based in Plymouth Township, Michigan, ROUSH Performance was founded in 1995 by motorsports legend Jack Roush.
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