K.J. Jones
March 12, 2007
Photos By: Holley Performance Parts
These NOS nitrous and fuel solenoids are the gateway to 75 additional rear-wheel horses for '05-'06 Mustang GTs.

Horse Sense: There appears to be no letup in sight for the enthusiasm over the various bolt-on power-adders available for S197 Mustangs. With a complete system priced barely over a thousand bucks, "spray" is still the front-runner in the best-bang-for-the-buck department.

Undisputable good looks, aboveboard handling, and Three-Valve, modular performance are three qualities of the new Mustang GT that enthusiasts have been raving about for two short years that already feel like an eternity. Sure, we're equally as enamored with the '05-and '06-Mustangs, and we're always looking for new S197 parts and technology from all points of the high-performance globe to tell you about.

Using nitrous oxide to enhance an engine's performance certainly isn't a new method of hopping up a Mustang on the cheap. 'Stangbangers have been spraying juice into small-block Ford engines for a few decades now, as it has proven to be the most cost efficient way to add instant power to stock or mildly modified 302, 351W, 4.6 V-8s, and even six-cylinder powerplants without sacrificing driveability. And it doesn't require elaborate ignition and fuel systems that can make the register cha-ching like a Vegas slot machine when the total investment figures are tallied.

After disconnecting the negative battery cable, the first order of business is to unplug the MAF-sensor wiring and remove the OEM air-inlet tube from the throttle body and airbox. With the tube removed, a mounting spot for the supplied nitrous nozzle can be determined and marked in the lower portion of the tube.

Nitrous Oxide Systems, a division of Holley, has developed an affordable nitrous kit (PN 02121NOS; $710) designed exclusively for new 'Stangs and their drive-by-wire technology (some people call it "fly-by-wire")-a computer-controlled throttle system that's been a major hurdle when attempting to install any power adder on these new cars.

NOS keeps safety and reliability at the forefront of this wet system, with jetting for 50 and 75 hp included, and the wick can be turned up to 150 additional horses, with optional jets for that power level. It has a double-dose of nitrous control via a primary drive-by-wire switch, as well as an rpm-activated window circuit that allows enthusiasts to program the system for on/off operation at any rpm.

Read on as NOS technicians take us through the simple process of installing their latest nitrous system on a stock '05 GT, and check out the results of before-and-after dyno tests. The kit bolts on in roughly three hours and no additional parts or exotic tools are necessary.

Any wet nitrous system requires a reliable fuel source. NOS includes an O-ringed, two-port billet adapter-for fuel outlet to the solenoid and an optional pressure gauge-that fits between the stock fuel sensor and fuel rail.

Installing this piece is as simple as removing two screws, placing the adapter between the rail and sensor, and resecuring it all with the supplied bolts.

The kit includes every fitting, line, wire, and bracket necessary for a DIY installation. Installing the supplied -4 AN fittings should always be done with Teflon paste instead of tape. Tape sometimes sticks inside a solenoid, holding it open and resulting in disaster. Each fitting also includes a built-in screen to help prevent debris from blocking flow.

With the nitrous and fuel solenoids plumbed, secure them to the steel bracket with the Phillips-head screws that are included. The inlet lines for nitrous and fuel should be pointed toward the rear of the engine, with the nitrous solenoid mounted on the inside.

A short, -4AN braided line mates the fuel solenoid with the fuel-rail adapter installed earlier.

A 7/16-inch hole is drilled in the bottom portion of the air-inlet tube, just in front of the mouth. This is where the supplied bung for the nozzle mount will be placed from inside the tube. Beware of placing the nozzle too far into the tube because you must reach it with a wrench when it has to be tightened. The NOS Soft Plume nozzle is positioned so the spray is directed toward the center of the throttle-body inlet, then it's tightened down.

Nitrous and fuel lines are attached to the nozzle before reinstalling the complete air-inlet assembly.

This is the Command Center for the NOS nitrous-oxide system for new Mustangs where the solenoids' wiring is routed and the throttle position or rpm is processed for reliable and safe nitrous activation.

The nitrous bottle is installed in the trunk.

NOS includes these factory-clean arming and purge rocker switches mounted in a billet panel that bolts directly into the new 'Stang's dashpanel without any additional drilling or drama. Once this piece is wired and installed, it's time to open the jug and get busy!

The NOS test subject was a bone-stock '05 Mustang GT with a five-speed transmission. In initial tests on a Dynojet dyno, the naturally aspirated 4.6 spun the wheels with a good baseline of 287 hp and 305 lb-ft of torque. Upon completing the installation and with the "big" 75hp pills (36N/30F) in the nozzle, however, the NOS nitrous charge livened up the stock Three-Valve with a power gain that maxed at a stout 344 hp and 415 lb-ft of torque at the back tires-not too shabby. You can clearly see the real fun begins when the nitrous clicks on at 3,200.

RPM Stock NOS Difference
Power Torque Power Torque Power Torque
2,000 97.14 255.11 98.15 257.75 1.01 2.64
2,{{{100}}} 103.69 259.32 104.55 261.47 0.86 2.15
2,200 110.82 264.56 111.81 266.93 0.99 2.37
2,{{{300}}} 117.12 267.45 117.60 268.54 0.48 1.09
2,400 123.22 269.64 124.01 271.39 0.79 1.75
2,500 128.87 270.75 129.46 271.98 0.59 1.23
2,{{{600}}} 133.68 270.04 134.59 271.88 0.91 1.84
2,700 140.27 272.85 142.18 276.58 1.91 3.73
2,800 148.56 278.65 149.96 281.28 1.40 2.63
2,{{{900}}} 155.21 281.10 156.16 282.81 0.95 1.71
3,000 159.63 279.46 160.79 281.50 1.16 2.04
3,100 163.65 277.26 165.67 280.69 2.02 3.43
3,200 167.86 275.50 220.51 361.85 52.65 86.35
3,300 174.06 277.02 {{{240}}}.17 382.24 66.11 105.22
3,400 182.85 282.45 250.81 387.43 67.96 104.98
3,500 192.20 288.41 263.55 395.47 71.35 107.06
3,600 201.46 293.92 275.67 402.17 74.21 108.25
3,700 208.35 295.74 285.50 {{{405}}}.26 77.15 109.52
3,800 214.63 296.65 295.88 408.95 81.25 112.30
3,900 219.52 295.{{{62}}} 306.01 412.11 86.49 116.49
4,000 227.16 298.27 316.17 415.13 89.01 116.86
4,100 234.{{{57}}} 300.49 {{{323}}}.04 413.81 88.47 113.32
4,200 242.51 303.25 329.69 412.28 87.18 109.03
4,300 250.32 305.75 334.06 408.03 83.74 102.28
4,400 256.02 305.60 337.96 403.42 81.94 97.82
4,500 260.93 304.54 342.76 400.05 81.83 95.51
5,000 264.76 302.30 344.03 392.{{{80}}} 79.27 {{{90}}}.50
4,700 269.14 300.76 341.81 381.97 72.67 81.21
4,800 274.20 300.02 341.22 373.37 67.02 73.35
4,900 278.15 298.14 342.31 366.91 64.16 68.77
5,000 281.48 295.67 341.30 358.52 59.82 62.85
5,100 285.70 294.23 340.38 350.53 54.68 56.30
5,200 287.05 289.93 338.99 342.40 51.94 52.47
5,300 286.56 283.97 336.42 333.38 49.86 49.41
5,400 287.25 279.39 336.91 327.69 49.66 48.30
5,500 286.17 273.28 336.76 321.58 50.59 48.30
5,600 284.79 267.10 336.24 315.35 51.45 48.25
5,700 284.32 261.98 334.85 308.54 50.53 46.56
5,800 283.28 256.52 335.02 303.38 51.74 46.86
5,900 281.50 250.59 332.14 295.67 50.64 45.08
6,000 280.74 245.74 329.13 288.10 48.39 42.36
6,100 245.39 211.41 322.95 278.09 77.56 66.68