Tips To Modifying Your Mustang - Starting Fast


Active Member
Mar 29, 2011
Reaction score
The Best Stuff To Put On Your Mustang Right Away

By Tom Wilson
August 1, 2002

OP Comments: I came across this article online and wanted to share it with you guys. It might help with any question new-to-the scene Mustang owners might have.


Where to start? It's the eternal question for Mustangers looking to maximize power, minimize money spent, and lay down a good foundation for power adders to come. And, as we read our mail here in the palatial 5.0&SF ivory tower, we understand there are always new enthusiasts looking for direction with their first Mustang power-parts buying decisions.

When it comes to outfitting a Mustang for everyday street duty, there is little controversy about the basics. Let's face it, 5.0 Mustangs have been around in their familiar EFI state for 15 years now, and the 4.6 machines are entering their sixth year of production. In all that time, the industry has worked out what's worth bolting on and what isn't. We can say that because we've just finished polling a wide variety of Mustang shops on what they offer their customers, and largely the advice is the same: gears, pulleys, and breathing. Of course, the devil is in the details, and that's exactly where we're headed in this article. Ultimately you'll need to decide precisely what combination of parts is best for your final performance goals, but this article is designed to help you make those decisions.

Have A Plan

It's vital to generate a plan when modifying your Mustang. Like a blank canvas, a stock Mustang can be worked into one of many different forms by a savvy owner, or turned into a mishmash by someone in a hurry who isn't quite certain of what they want.

So, before browsing the ads and catalogs, take the first real step: Tell yourself where you want your Mustang to end up when you are finished working on it. Nice daily driver? Drag car? Occasional slalom tool? All are worthy goals but require somewhat different parts. For example, a daily commuter, especially one destined to go on long road trips, is going to want taller gearing than a daily driver that sticks mainly around town and sees several slaloms a year.

By choosing a performance path to follow, you'll make fewer wrong financial turns along the way.

We Ask The Question

To provide the direction for those important first steps, we polled Ford specialty shops and parts manufacturers. Our question was, "What combina-tion of parts do you recommend for the 5.0 or 4.6 owner who's just starting out-the guy who needs simple, affordable improvements?" We wanted to stick mainly to bolt-on parts-and we figured we really didn't have to tell you a $4,000 blower is a good way to improve power.

A few shops took this time to point out they don't see a tremendous number of stone-stock 5.0s anymore, but the 4.6 cars still show up just the way Ford bolted them together. Others reported the occasional stock 5.0 still comes calling. So if you are going to buy a used 5.0, don't be surprised if you have to search some to find a totally stock one, although nicely prepped ones are definitely out there as well. If the car already has the parts you want, you'll no doubt save money buying them that way, rather than piece-meal over the counter-and, the labor is already done.

When getting down to the hardware during our poll, the answer almost always started out with a barrage of return questions: "What year?" "5.0 or 4.6?" "Daily driver or street/strip car?" "Automatic or manual?" We could only say we were talking hypothetically, and from there the tuners tended to zero in certain hardware combinations they found most useful-or pointed out dead ends to avoid.


Bang for the buck, there is no better whack in the back than a set of final drive gears in the ol' 8.8-inch differential. That's a universal recommendation, so if you have truly limited time and money-and that's a lot of us-then just a set of gears is a smart move. They won't make any more power, but they'll better use what you do have.


The lingering effects and mental attitudes of two fuel crises were still around when the first EFI 5.0s hit town, so a ton of the earlier Fox Mustangs came with 2.73 gears. These are real freeway flyers, the sort of lazy cruisers that keep rpm to 1,800 on the interstate and make you run all the way through each gear in town. They have no performance potential, unless you're running at Daytona and want to use Second, Third, and Fourth gears instead of Third, Fourth, and Fifth. We did that once with Dario Orlando of Steeda Autosports-and, believe us-6,000 rpm in Fourth with 2.73s can be plenty entertaining, but not around town.

By 1990, 3.08s seemed the standard in manual-transmission 5.0s. Again, their main claim to fame is fuel economy, and each transmission gear is needed for daily driver acceleration.

The lowest optional gears available off the showroom floor have been 3.27s. On a 5.0 these are the tallest of what could be called performance gears. That said, it's a small percentage of enthusiasts who really prefer this ratio. They have a mainstream feel, although 3.27s are low enough that you can skip gears when accelerating at the depressingly common tortoise rates of modern traffic. They are nicely relaxed on the freeway, and for a long-distance commute-as is common out West-3.27s could be a workable choice. If you're stepping up from 3.08s, you won't feel much difference, though. Typically it takes a two-step jump-from 2.73 to 3.27, for example-to really feel the difference.

Another place 3.27s could help is with high-torque engines that would simply blow the tires away with steeper gears. It takes high blower or turbo boost to make this sort of power, so you have to be aiming near the outer limits to really need these gears for that reason.

Then we come to 3.55s, the best all-around gear in a manual transmission 5.0. Acceleration is notably sparked up, yet the freeway cruise is easily within normal engine rpm, even at today's elevated, super-legal freeway velocities. Even if your combination is naturally aspirated or packs 10 pounds of boost, 3.55s work.
These are also the first ratio where you might consider skipping First gear in a 5.0 occasionally. This will only happen on downhill starts, but the point is the gears are short enough to be a real help in moving a Mustang.

So, light-duty acceleration may mean you can jump from Second to Fourth gear and save some work while getting into a better fuel-economy profile. In fact, for around- town Mustangs that are always accelerating away from traffic lights, 3.55s often do well on mileage because the engine doesn't have to work as hard. At the same time, First gear isn't so short that it feels more like a nuisance than a help.

On the other hand, some enthusiasts are not concerned about fuel mileage. They figure there's little financial incentive between 17 and 21 mpg, so they'll take the racier gear and not worry about the fuel burn.

The Second great 5.0 gear ratio choice is 3.73s. Now we're getting definitely sporty. First gear is short but really digs in when trying hard. The freeway "cruise" is getting well above 2,000 rpm when you're late to work. But for nearly all but the most laid-back enthusiasts, 3.73s are still quite street able.

If your ultimate plans call for a blower, then 3.73s could be too much, especially in a lighter car. If you'll have just basic equipment, and are foregoing the 400 pounds of stereo gear; another 100 pounds of rollcage; and who-knows-how-heavy, cast-aluminum aftermarket rims, then 3.55s will suffice with a blower on the street. At the track you'll probably still want to go deeper.

Then there are 4.10s. Well, too much is just right for a lot of folks. If squirting a couple of gears away from a light is all you're doing, and you just have to have it all, then 4.10s will absolutely put the snap in an otherwise near-stock 5.0 powertrain. They are too much with a blower, and the engine will buzz along at 2,500 rpm at 70 mph with standard-height tires. If powerslides are your thing, 4.10s will light 'em up in Second gear with ease.

One place 4.10s give good gearing is on a street/strip car running a smog-legal, near-stock engine and tall slicks. The combination is track-oriented, but still easily capable of driving itself on public roads between tracks using stock height tires. The tall slicks will just allow Fourth gear through the lights at the track; stock-height tires and 4.10s mean a performance-killing shift into Fifth at the big end of the track.

On road courses, 4.10s are too much. You'll need Fifth on the longest straights, and tire spinout of the slow corners is a problem.
If your 5.0 has an automatic, step everything up one gear ratio. That makes 3.73s the default cogs for almost every performance automatic Mustang.
Likewise, 4.6 Mustangs simply cannot match the excellent low-end torque of the 5.0. This is most telling right off idle and up through a couple thousand rpm, where the 4.6 is a bit flat compared to a 5.0. That means more rear gear is useful.

At the other extreme, the 4.6 is smoother at higher rpm than the 5.0, so it can wing along a little faster on the freeway and not feel like a McCormick reaper at full chat. That makes the 3.73 gears the best choice for all-around manual-transmission 4.6 GTs, and a great choice for daily driver automatics as well.

The 4.10s in a 4.6 car are still somewhat short, but if you don't mind a 2,500-rpm freeway cruise, they do give the little V-8 enough leverage for sporty acceleration while still not threatening wheelspin every time you open the throttle. This is especially true with 4.6 Cobras and their extra-high-rpm range. As Fairway Sport & Performance put it, "On the Cobras ... go with 4.10 gears ... You're not tapped out in Fourth at the end of the quarter, and not excessively low geared in Fifth."


By reducing parasitic losses to the water pump (mainly), underdrive pulleys free up a bit of power. They are also one of the least expensive and easiest to install of the bolt-ons. Typically you'll see 7-12hp gains on a chassis dyno with pulleys.


By all means, stick with street pulleys and stay clear of race-ratio pulleys. By definition Ford puts just enough gearing in the pulley system to keep the alter-nator charging and the water pump circulating coolant at idle. To achieve their performance gain, underdrive pulleys cut into Ford's worst-case-scenario pulley ratios, so you'll typically see the alter-nator go off-line at idle, and the cooling will be sketchy in truly hot weather and stop-and-go traffic. Thus, Phoenix and Miami Mustangers, and those seeing plenty of stop-and-go driving, may be happiest with stock pulleys.

Joe Gosinski at Chicane Sport Tuning pointed out that 4.6 owners need to pay special attention to the harmonic damper/crank pulley assembly in aftermarket pulley kits. Most of these use aluminum dampers, which are rapidly worn by the crankshaft seal. As Joe says, "Either use a steel damper or a stainless steel sleeve" on 4.6 crank pulleys to avoid what could be a persistent oil leak.

Cold-Air Intake

Several shops listed cold-air kits from K&N, MAC, or BBK as worthwhile on 5.0s. No one claimed big power gains from these, but they are popular because they don't cost much. As GRC Performance put it, "...on 5.0s, cold-air induction systems are not too much money, and they're pretty effective."


If you are ultimately keeping your Mustang naturally aspirated, then a cold-air kit should free up a few horsepower via a less-restrictive intake path. However, if you are working your way to a supercharger one of these paychecks, then you might want to save the cold-air-kit money as your blower kit could include a new air-inlet system anyway. It would be worth a look at the blower kit before opting for the cold air.

When shopping for a cold-air kit, keep in mind that a true cold-air intake draws air from somewhere besides the engine compartment. That's the whole idea-avoiding hot, turbulent underhood air the way the stock system does, but with larger, smoother tubing and less-restrictive air filters. If for some reason you do end up with an underhood open-element air filter, make sure it has a fan-wash shroud. That's a piece of metal or plastic that shields the air filter from direct engine-cooling fan action. If you don't have this, you can end up with an erratic idle and other driveability hair-pullers.


Active Member
Mar 29, 2011
Reaction score
Mass Air Meter/Throttle Body

A larger mass air meter and throttle body are old standbys on 5.0s, but interestingly you'll get mixed reviews on them if you ask around. Part of this is due to the wide range of meters and throttle bodies available-it's easy to go too large on a daily driver Mustang. When that happens, torque is lost and not much top-end horsepower is gained because the restriction is somewhere else when just getting started with breathing mods.


On 5.0s, the mass air advice was most thoroughly given by GTR. "We use a C&L mass air meter, either 73 or 76 mm. If you have big plans in the future, go with the 76; if you are going after just a few bolt-ons, then the 73. The 76 supports more horsepower ... but the 76 is overkill with just mufflers and air filter. ... To retain low-end torque on a simple bolt-on car, stick with the 73. Besides, it's $20-$25 less expensive for the 73mm."

Throttle bodies on 5.0s are less important right away, with the stock 55mm unit hanging in there until the exhaust and mass air have been improved. Even then, the vast majority of bolt-on 5.0s do just fine with a 65mm throttle body, and it's a rare street-legal car that actually needs more than a 70mm throttle body can flow. If you're going the light bolt-on route, especially with a heavy convertible or loaded-down stereo car with an automatic, get a 65mm throttle body after you've gotten the gears, pulleys, headers, and so on.


On the other hand, prospective blower buyers with 5.0s would do best to buy a 70mm throttle body. This ensures adequate airflow, and the loss of driveability when off-boost is unnoticeable. In fact, 70 mm has become such a popular size that you almost have to work some to find a 65mm unit.

Things are different with Two-Valve 4.6 cars. These higher-revving engines respond better to a larger throttle body than a 5.0, so you can make a throttle body a first purchase on a 4.6. The same holds true for an intake manifold. Ford Racing Performance Parts throttle bodies are obvious choices for 4.6 engines.


Headers are one of the first "larger" bolt-ons a 5.0 receives, and for good reason. The airflow choke on the 5.0 H.O. engine is the exhaust, especially the port in the cylinder head and somewhat less the crimped factory exhaust headers. It takes an aftermarket cylinder head to get rid of the lousy exhaust port, which is a superb bolt-on improvement, but more money and wrenching than we're talking about in this article. For now, stepping up to headers and an after-cat exhaust is the 5.0 game plan.


There are plenty of 5.0 header choices, but what you want for a bolt-on car are 1 5/8-inch unequal-lengths. They give the type of power boost you can use, are relatively easy to install, are widely available, and are the least expensive of aftermarket 5.0 headers.

As GTR says, "The entry guy always goes to the unequal-length headers. We sell MAC and Ford Racing [Performance Parts]. The equal-lengths take longer to install, are more expensive, and kill low-end torque. Not a good first mod. The equal-lengths are good with forced induction and a big stroker, but they're hard on torque-not what you want for a 250hp engine. Save money and save your knuckles; just install the unequal-lengths."

Everyone seems to bolt on an after-cat early in the game too. This is useful only to make more noise, so choose an after-cat system that makes the noise you like. Rumbling Flowmasters or humming turbo mufflers-take your pick, as the power difference at this modi-fication level is virtually nonexistent. Stick with a 211/42-inch diameter system to avoid a torque loss. Only serious forced-induction cars need expensive, cumbersome 3-inch exhaust systems. In fact, convertible Sunday cruisers probably do just as well with a 211/44-inch system, but everything you'll find is 211/42 inches, so have at it.

Owners of 5.0s are heavily into replacing H-pipes these days, as the cars are typically over the Federal government's 100,000-mile hurdle and the original cats have nosed over in efficiency. Do not run off-road (non-cat) H-pipes! Yeah, they might make 10 more horsepower than a high-flow cat model, and they're less money, but we're all trying to breathe here, OK? Use a 2 1/2-inch high-flow cat H- or X-pipe on a bolt-on car. You stay legal, the air stays a lot cleaner, and you can make up the 10 hp in other ways.

For the 4.6 crowd, exhaust is not quite as important because of the physical sizes of the large engine and tight chassis. To put it bluntly, if a short-tube header fits in a 4.6 Mustang GT, the header doesn't work (that gem came from a Ford engineer charged with developing Mustang exhaust, so he should know). To make a 4.6 exhaust work-GT or Cobra-a long-tube, four-into-one header is required. These aren't even close to legal on the street, so forget it. The oxygen sensors don't fit, the H-pipe must be changed-just forget it.

Furthermore, the stock 4.6 exhaust manifolds are not that bad. Yes, they are a simple log design-and, yep, cast iron is heavy-but they seem to flow fairly well thanks to smooth bends, and they're quiet, leak-free units. Installing 4.6 headers is a total pain, too, what with having to lift the engine off its mounts and tight, knuckle-cutting clearances everywhere. Just hook up an after-cat rumble pack if you want, but don't worry about the rest of the exhaust on a bolt-on 4.6 Mustang.

The exception is that there are good, high-flow, smog-legal X-pipes for the 4.6 cars, so you could go that route on an early, high-mileage 4.6. This is especially good if the stock cats become clogged, because they're power killers at that point.

Head, Intake, and Cam

OK, it's a stretch as a first set of bolt-ons, but Anderson Ford Motorsport was so persuasive in talking about the next step that we thought we'd mention where the bolt-on Mustang inevitably ends up.


As Rick Anderson put it, "Start with the true and blue on the 5.0 cars: 3.73 gears, underdrive pulleys, better throttle bodies, after-cats, headers. From there, go to Twisted Wedge heads, then the N-41 cam [an Anderson Ford Motor-sport custom grind] ... and Track Heat, or the new Typhoon intake, 'cause it's so cheap.

"The N-41 offers good driveability and runs from 1,800 rpm, pulling hard from 2,800 to 6,200 rpm. It's a "neat-sounding little cam-one of our biggest sellers," Rick says. "And its piston-to-valve [clearance] is a bolt-in with the Twisted Wedge heads."

In the heartland, such camming advice no doubt yields hard-running 5.0s, but it has to be a tough sell anywhere smog checks are the norm. Especially for the guy starting out, stick with the stock cam for best driveability, fuel mileage, and even power, until you absolutely have run out of every other trick.

With the '96-'98 4.6 Mustangs, modifications are cut and dried between two distinct levels, says Rick. "The best thing is gearing, an after-cat, then an X-pipe, and then a K&N cold-air kit. After that, you have to do the heads and intake or go with a supercharger. The FRPP heads and intake are a good package.

"For the '99-and-later cars, Rick recommends the same starter package, "but with a better throttle body and better mass air (Pro-M 80mm) ... then the Bullitt intake off the Bullitt Mustang. It's more than the 5 hp that Ford claims...It allows more cam and head."

Ultimately If you find yourself really enjoying the extra power from your 5.0 bolt-ons, then figure on changing the cylinder heads someday. Good heads are the magic key to substantially improved 5.0 power, so once you have the gears, pulleys, throttle body, mass air, and exhaust, you might as well start saving up for heads. Undoubtedly, you can add an improved intake manifold and gain around 12 hp, but you can bolt on heads and an intake and easily gain double that and likely much more.

Heads and an intake will not only give substantially more power, but they'll also bring an extra 1,000 useful rpm over the 5.0s' agricultural 4,500-rpm power peak for a much more exciting and fun-to-drive powerband. And fun is what it's all about.

Just the Facts, Man

Kept to basics, the industry recommendations for a first set of bolt-ons are as follows:



• Rear axle gears
• Pulleys
• Headers
• High-flow H-pipe
• Cold-air intake
• Mass air meter
• Throttle body


• Rear axle gears
• Pulleys
• Cold-air intake
• Mass air meter
• Throttle body
• Intake manifold and cylinder head

Parts No One Mentioned

Note that panel air filters, larger fuel injectors, adjustable fuel-pressure regulators, and many other useful parts were not mentioned by any of the shops we polled. It's not that these parts don't work; it's that they aren't as effective when paired with basic bolt-ons.

They Said It

All Mustang Performance

"We have a 2001 GT with an AOD ... Steeda underdrive pulleys (and exhaust) runs 13s. We put a throttle body on and it hurt it ... blown might be different."

Chicane Sport Tuning

"Anderson Ford has a new set of cams (for the 4.6) ... quick, easy install, not like putting a cam in a 5.0; it's more of a bolt-on ... can do a real mild cam, something not too aggressive..."

Dugan Racing

"Best money spent is a gear change, of course ... Stock motor, the 3.55 is perfect on a 5.0, but if they do any kind of exhaust work or other bolt-ons, then I highly recommend 3.73s because they'll be turning more rpm."

"Most of our business has been 4.6 stuff recently. Especially when Ford came out with the zero-percent interest for three years, they just sold like crazy for a while. We got quite a bit of customers on that."

"On a 4.6, the headers ... we don't push just on motor. But on a supercharged application from dyno tests, we do know they make power. But for the cost and labor, just on motor, they're not worth what you pay ... High-flow converter pipes don't cost so much and work better than headers just on motor."

"We've done a bunch of crate motor installs on 5.0s, GT-40Ps...It's a popular one. A lot of people are looking for the GT-40P head because it is relatively affordable and gives pretty good power ... with a Cobra intake and E camshaft, they really run good."


"On 4.6 cars, we can change the speedometer [gears] with the bigger [rear axle] gears... We do it [speedo recalibration] through the chip. This is important with the lower gears."

"Subframe connectors are important ... stop the flexing, keep the future of the car to protect it ... lowered or not. It's what holds the car completely together."


"Here in California, most guys are driving their cars [all year]. Most California customers shy away from gears, so they go to big mass air meters, pulleys, exhaust systems, high-flow H- or X-pipes with two cats instead of four- or six-cat stock systems. Then they'd get into an aluminum driveshaft because they're quick and easy."

"Almost every customer is asking [about aluminum driveshafts] because the U-joints [on their old 5.0s] are at 125,000 miles, and new joints are halfway dollar-wise than a new shaft with new joints."

The V-6 Thing

A few shops mentioned the popularity of bolt-ons for the ’99-and-later V-6 Mustangs. Vastly improved over the earlier bent six machines, the late V-6s are great second cars that many owners inevitably want to spruce up.

Because they are owned for cost, mileage, and insurance reasons, it’s not unusual to find V-6 Mustangs commuting 80-90 miles a day. This puts a premium on simple performance mods that don’t interfere with emission laws or drivability.

Some of the favorite V-6 mods are as follows

• C&L 73mm mass air meter, good for 9-10 hp. This comes with a high-flow air filter and heat/fan wash shield.
• Pulleys, worth 8-9 hp.
• Dual-exhaust after-cat kit from MAC. Bolts directly to the stock V-6 H-pipe; good for 8-9 hp.
• 3.45 gears for the 7.5-inch rear axle. This ratio is good for lots of freeway driving. Or, for more acceleration, go with 3.73 gears. Often a Traction-Lok is added for an additional $200.


Well-Known Member
May 19, 2013
Reaction score
Dayton Oh
Not sure why it's saying long tubes aren't worth it. True they're more of a PITA to install but they aren't much more and in most cases they're the same price if you are going to buy a mid-pipe as well. Over all some good info.

Latest posts

Forum statistics

Latest member

Members online

No members online now.