KJ Jones
Brand Manager, 5.0 Mustang & Super Fords
June 1, 2009
Photos By: KJ Jones

Horse Sense: Quite frankly, factory-fresh '99-'04 Mustangs now bring the same level of excitement to us that stone-stock Fox 'Stangs used to bring. Consider it a slight changing of the guard, if you will, but the reality is more so that when one lake dries up (finding a bone-stock '86-'93 GT or LX is increasingly more difficult), another one, Lake New Edge, is stocked and ready for 'Stangbangers to cast their lines and go fishin'.

A perusal of several online and print Mustangs-for-sale classified ads brings us to this month's revisit of simple, bolt-on performance upgrades for '99-'04 Mustang GTs. Recently we noticed an increase in the availability of good post-Fox Mustangs that are selling for well below $10,000. Not surprisingly, many of these Ponies are still in their original trim with mileage between 60,000 (on the low end) and upward of 100,000. These are cars that have dutifully served as nothing more than a means of daily transportation for owners who aren't as hyped as we are about making 'Stangs better.

The way we see it, New Edge 'Stangs are now really coming into their own as good Mustangs to modify on a budget. (Of course, '79-'93 Fox bodies will never lose their top-tier status as the best foundation for all sorts of 'Stang projects.) So for this project, we've selected what we think is an impressive $1,540 group of entry-level upgrade pieces-cold-air intake, throttle body/plenum, after-cat exhaust system, underdrive pulleys, and PCM flash tune-that should bring a nice power and torque gain to the rear wheels of Henry De Los Santos' unmodified '99 Two-Valve-powered 'Stang. (Note that we provide the manufacturers' suggested retail prices. Deep deals for this hardware are everywhere you turn, so scoring this package for less is quite doable if you shop around a bit.)

While brands that are used for initial modifications vary based on a Mustang owner's personal preference or research, air-induction components lead the charge, so to speak, among the parts that comprise an entry-level, 4.6-liter performance system. For our report, we're working with BBK's new, unique one-piece throttle-body/plenum unit, as well as its tried-and-true cold-air intake kit for '96-'04 Mustang GTs, to determine the positive or negative influence it has on our well-worn stocker.

With respect to induction, air taken in must have an efficient method of exit (as exhaust gas). To improve exhaust flow and engine sound over the factory equipment, Flowmaster's American Thunder Series after-cat exhaust system is the solution for our stocker. And, as underdrive pulleys always prove to be solid performers in the stock-'Stang hop-up game, we're turning to AmericanMuscle.com as a source for Steeda's pulley swap pieces. We'll see how eliminating stress on the crankshaft affects the Two-Valve at the feet.

Modern-age EFI performance also requires changes to the fuel and spark calibrations in a Mustang's PCM. DiabloSport's Predator is a hand-held device that allows users to load pre-programmed tunes with calibration adjustments that will allow the test-Pony's Two-Valve engine to run properly with our upgrade pieces. The Predator also enables Henry or a tuning specialist to log engine data, and based on that info, make additional changes inside the processor as to what the engine needs (timing, fuel, and so on).

Of course, since our focus is on power/torque at the rear tires, the chassis dyno at Extreme Automotive will serve as the almighty recorder of all data for this project. Although we're fortunate enough to have great assistance from Saul "The Surgeon" Gutierrez of Extreme as your tech editor photographs and makes notes on various aspects of our projects as they're being done, each part that we're working with in this recap definitely can be installed by a confident home mechanic over the course of a single day.

As time and trends take us deeper into the S197 era and beyond to the pending arrival of '10 Mustangs at Ford showrooms nationwide, our remembrance of Mustangs past, especially from a technical aspect, becomes more and more important. So, yes, we've covered the basics many times before, with Fox-body as well as New Edge Mustangs. We're going to continue to experiment with various simple mods, because in today's tough financial environment, making the best-bang-for-your-buck decisions to hop up your Mustang is more important than ever.

On The Dyno
We took dyno readings immediately after installing each part and saw an interesting fluctuation in the rpm ranges where power/torque gains occurred, as well as the amount of gain and loss of each that the parts yielded. While the Flowmaster after-cat exhaust and AmericanMuscle.com-acquired pulleys boosted rear-wheel horsepower at the higher-rpm segment of a dyno pull (the pulleys proved to be the most productive individual element in our quintet), power gains were achieved roughly 325- to 330-rpm sooner once the BBK cold-air system, new 78mm throttle-body unit, and DiabloSport's plug-in PCM calibration were in place. It's also interesting to note the difference in horsepower and torque we saw when BBK's new throttle body/plenum setup was added.

The bottom line with this group of affordable Two-Valve pieces: Overall it delivered nearly 25 additional horsepower to the rear wheels and almost the same amount of torque lb-ft in a 100,000-mile tester burdened with an unfavorable (for dyno purposes) automatic transmission-and six catalytic converters. Hindsight obviously says that even with an AOD tranny, an off-road X-pipe also should be considered with this type of bolt-on upgrade.

However, based on the dyno numbers and the dramatic way in which the collection improved our '99 'Stang's driveability and street performance (see On the Street sidebar), we think it definitely earns a spot on the list of Two-Valve hop-up packages that will give any stock naturally aspirated, pump-gas New Edge a lot more get-up-and-go.

2,428 116.77 243.34 115.13 239.16 121.14 242.47 112.16 233.59
3,417 161.32 238.99 161.40 238.28 165.81 244.73 159.08 233.61
3,621 170.04 238.10 171.04 238.25 175.50 244.14 172.41 239.16
3,834 180.34 238.23 181.63 238.96 187.71 245.84 183.78 241.01
4,135 191.12 233.98 193.87 236.50 {{{200}}}.39 243.72 198.20 241.04
4,245 193.66 231.21 196.96 234.03 203.74 {{{240}}}.72 203.56 241.37
4,436 195.96 233.75 199.50 226.84 206.93 234.84 211.17 239.46
4,637 197.89 216.30 201.25 214.93 209.18 224.86 215.70 233.95
4,812 198.99 209.28 202.79 212.54 210.12 219.77 216.71 226.73
4,917 199.79 206.06 203.85 209.11 211.11 216.35 216.63 221.10
5,017 200.35 202.36 204.77 205.85 211.74 212.66 215.88 215.98
5,142 199.96 197.31 205.41 201.50 212.14 207.92 214.63 210.32
5,208 198.35 193.12 204.58 198.13 211.07 204.18 213.07 205.77
5,282 196.30 188.46 203.16 193.99 209.66 199.88 211.42 201.20
5,309 195.53 186.79 202.63 192.50 209.19 198.39 210.36 198.27
2,428 110.37 227.99 113.67 233.44 -3.10 -9.89
3,417 162.42 237.64 162.35 237.15 1.03 -1.84
3,621 175.96 243.77 177.32 243.98 7.28 5.88
3,834 189.20 246.91 189.39 246.11 9.05 7.88
4,135 205.60 248.61 204.29 246.36 13.17 12.38
4,245 209.67 246.56 210.12 246.85 16.46 15.65
4,436 215.31 243.33 216.87 244.14 20.91 10.40
4,637 219.55 237.19 222.18 239.64 24.28 23.34
4,812 223.07 232.24 223.10 232.04 24.11 22.76
4,917 222.93 226.50 224.02 227.04 24.23 20.98
5,017 222.86 221.94 223.76 223.37 23.41 21.01
5,142 221.29 216.14 221.93 216.37 21.98 19.07
5,208 220.02 211.{{{80}}} 220.76 211.98 22.42 18.86
5,282 218.28 207.07 219.14 207.38 22.84 18.92
5,309 217.70 205.42 218.58 205.82 23.05 19.03

On The Street
We thought it would be cool to give you the car owner's impressions of the difference a few simple bolt-ons has made to his 'Stang. Our buddy, Henry De Los Santos, uses the now-upgraded '99 GT on a daily basis, so his comments are appreciated, and other stock New Edge owners should take heed if you're considering doing the same to your '99-'04 Two-Valve Ponies.

Over the years, I've managed to log well over 100,000 miles on my '99 Mustang GT. The car is in its factory configuration, with nothing more than a few wheel swaps and the addition of select Terminator body components as the only "upgrades." Don't think that I didn't want to add any bolt-on horsepower goodies, because I certainly did. This '99 being the newest car I had ever owned at the time, the holdback was that I quickly learned to appreciate its comfortable demeanor in bone-stock trim.

The dyno is one thing, but based on what I'm now experiencing when I drive the car, I can say the mods done in this project definitely have given my GT a completely different personality. I'm enjoying the car now more than ever since I've owned it. I appreciate the fact that gas mileage has increased by 2 mpg, and the exhaust tone is perfect-aggressive enough to alert others that this isn't a lackluster V-6 Mustang.

More importantly, I'm impressed with the overall driveability. There used to be an unexplainable idle surge every so often after initial startup, and it would continue to occur randomly at most stoplights. Those symptoms are completely eliminated. I'm definitely going to credit the DiabloSport programmer for this, not to mention I really dig being able to use the device to adjust the shift firmness of what used to be a sluggish automatic.

When it's all said and done, I think the parts that KJ selected are a perfect package for anyone who's looking for a good no-nonsense, bang-for-the-buck upgrade.