K.J. Jones
June 14, 2007
Saul "The Surgeon" Gutierrez guides Ivan Lopez into the installation stall at Extreme Automotive for a Two-Valve performance makeover with entry-level performance products for '99-'04 Two-Valve 'Stangs.

Horse Sense: We know you'll probably read this story on Two-Valve power gains and say, "That's cool, but what's the deal with 5.0&SF's supercharged '02 Mustang project?" Fear not! While reports on our ProCharger-blown Two-Valve 'Stang will be continued soon, please understand the importance for us to address the basics from time to time. Remember, the 'Stang fraternity gains at least one new member each and every day. That's one of the reasons why we enjoy doing this so much

Lately, we've encountered Mustang enthusiasts-both neophytes and hardcore OGs-who firmly believe that the horsepower "buck" for stock 4.6 Two-Valve 'Stangs begins and ends with superchargers. These are the 'Stangbangers who pontificate on enthusiasts' Internet forums, singing high praises of boost. They quite often make performance claims about supercharged, stock 4.6s that go beyond the realm of possiblity, let alone believable.

This bone-stock 4.6 generates a paltry 213 hp and 242 lb-ft of torque to the rear wheels of Ivan's 47,100-mile, five-speed convertible. We're fairly sure the upgrades will improve these low numbers.

Sure, a blower will wake up a stock 'Stang in relatively quick fashion, and in the past we've detailed the type of gains that can be achieved when you bolt a blower on a virgin modular. For this exercise, we're going to take a closer look at the cheaper alternatives for putting more zoom in your untouched Two-Valve. That's right, it's time to throw the originals at a stock, mod-motor Mustang.

Now, when we say "the originals," we're talking about the bolt-on parts that have become recognized as budget-friendly power producers throughtout the years. After-cat exhaust, throttle body and plenum, cold-air-induction system, underdrive pulleys, and a high-performance tune are a few examples of these.

This Two-Valve test comes to you on the heels of our recent Three-Valve, bolt-on report ("The Power of Three," Mar. '07, p. 134), when we installed cold-air and exhaust components as well as underdrive pulleys and an SCT tune on a stock '06 GT. The upgrades netted 30 additional rear-wheel horsepower on Gonzolo Topete's S197 at a cost of roughly $1,300. We've decided to keep the theme rolling and take a look at how the 4.6 in Ivan Lopez's '03 ragtop GT responds to similar treatment.

Exhaust leads off our project. This is the Vortex 2-inch after-cat exhaust system by Cherry Bomb (PN 300502; $380). The bolt-on system fits '98-'04 'Stangs and includes everything required for an easy installation (tubes, clamps, hangers, an so on).

New Edge Mustang GTs are currently raising the popularity bar fairly high. Not only are '99-'04 'Stangs plentiful, many are still in the bone-stock trim that 'Stang-bangers lust for, for modifying, personal-izing, and upgrading. Another great quality is price. Although our test subject was purchased new from a dealer in 2003, we shopped around for today's ballpark price on a stock 'vert GT with 47,100 miles and found that $12,000-$15,000 can put you in the same car. Depending on mileage, some coupes can be had for less than $10,000.

The 4.6 upgrade parts we're using come from Accufab (throttle body/plenum), Cherry Bomb (Vortex after-cat exhaust), DiabloSport (Predator), JLT (ram-air intake system), and March Performance (underdrive pulleys). Saul "The Surgeon" Gutierrez will install each part, and we're immediately evaluating any gain or loss of horsepower or torque using the Dynapack Evolution 4000 chassis dyno at Extreme Automotive in Canoga Park, California.

The 'Stang is loaded on the twin-post hoist, and The Surgeon has disconnected the negative battery cable. Without further ado, let the bolting-on begin!