Steve Temple
May 3, 2007

Step By Step

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Mmfp_0706_stain_01_z 2004_ford_mustang_gt_convertible Front_viewMmfp_0706_stain_03_z 2004_ford_mustang_gt_convertible Engine
The Kenne Bell-blown 4.6 puts 460 hp to the rear wheels.
Mmfp_0706_stain_05_z 2004_ford_mustang_gt_convertible Rear_viewMmfp_0706_stain_07_z 2004_ford_mustang_gt_convertible Panhard_bar
An adjustable Panhard rod keeps the rear located under extreme cornering.
Mmfp_0706_stain_04_z 2004_ford_mustang_gt_convertible Interior

Top-down motoring in a convertible Mustang can be a fantastic sensory experience--wind in the hair, sunshine on your shoulders, and blue sky overhead. But don't forget the shudder in the cowl, too. This latter trait has been a problem with Mustangs (except for the latest model, which was designed with extra chassis rigidity). Previous models relied more on the hardtop structure for chassis stiffness, so if it's chopped off and replaced with a cloth top, the result is a flexible flyer, even with reinforcements the factory added to compensate. Even the extra weight of the bracing didn't exactly make for agile handling.

Nevertheless, a convertible has undeniable appeal, especially on a road trip or on a warm, sunny day near the beach. So when Mike Jonas of Stainless Steel Brakes decided to go on the Hot Rod Power Tour, he went shopping for an open-top Mustang at his local dealer in Buffalo, New York. Considering this city has some of the heaviest annual snowfall in the United States, convertibles are not exactly in high demand, so it came as no surprise that there was only one on the lot, and the dealer wasn't ready to part with it.

That irked Mike, and it led him to start the tour driving a modified Integra. Since a Japanese import would hardly be the belle of the ball at this annual celebration of American iron, one of his company reps hooked him up with a Ford retailer in Texas that happened to be the largest F-150 dealer in the country. Among the acres of pickups, Mike came across several yellow convertible Mustangs. After picking out a GT, and with a bit of negotiating, he charged the sales price on his American Express card and joined the tour on its northern passage.

While the convertible GT fit in better than the tuner car with all the domestic musclecars and hot rods, Mike still heard a lot of ribbing for bringing along a stock "sissy car." Not used to driving plain vanilla, he faded to the rear of the convoy. But right then and there, he vowed to return with an utterly transformed ride, one with impressive power and road-course performance, despite the lack of a hardtop.

The three-month buildup began at the foundation, starting with a Kenny Brown suspension setup welded to the undercarriage. Mike welded to the B-pillar a lightbar from Chassis Design Concepts. Strut tower braces could not be fitted, though, because they would interfere with the supercharger he planned to install.

Step By Step

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Mmfp_0706_stain_09_z 2004_ford_mustang_gt_convertible Side_viewMmfp_0706_stain_08_z 2004_ford_mustang_gt_convertible Drivers_seatMmfp_0706_stain_02_z 2004_ford_mustang_gt_convertible Driving_shot
Mike Jonas of Stainless Steel Brakes has prepared the perfect cruiser. His GT has power, handling, and some mighty sharp looks.
Mmfp_0706_stain_06_z 2004_ford_mustang_gt_convertible Ssbrakes
The GT uses Stainless Steel Brakes Tri Power brakes up front with three-piston calipers clamping down on 13-inch rotors. At the rear are 12.2-inch rotors with single-piston calipers. These upgrades can bring the machine from 60 mph to 0 in 113 feet.
Mmfp_0706_stain_10_z 2004_ford_mustang_gt_convertible Mach_1000_audio_system

These changes markedly stiffened the chassis and minimized the annoying cowl shake, but with lots more power in the plan, Mike also upgraded the suspension with Mustang Racing Tech's lowering springs, gas shocks, and an extra-thick 1 3/4-inch swaybar. Billet-aluminum caster/camber plates helped dial in the alignment to optimum settings so the car would run straighter and corner tighter. It also minimized the understeer that caused the convertible to plow in the turns.

Now the drop-top was ready for a massive infusion of power, courtesy of a Kenne Bell blower. Set at 9 pounds of boost with a 2 3/4-inch cog, the twin-screw supercharger raised the engine output to 460 horses at the rear wheels. "This car pulls like you would not believe," Mike says. To transmit the increased power flow, he added an aluminum driveshaft from Year One. For freer-breathing exhaust, MagnaFlow supplied an after-cat system with a crossover pipe.

With all that extra go, Mike needed more slow. Pulling out all the stops, he raided his company's parts bin, installing a Stainless Steel Brakes Tri Power system up front with three-piston calipers clamping down on 13-inch rotors. At the rear are 12.2-inch rotors with single-piston calipers. These upgrades brought the MRT 17-inch wheels to a clenching halt, 113 feet from 60 mph, Mike says.

In addition to upgrading the car's performance, Mike integrated elements from a couple of different body styles. The Mustang Racing Tech chin spoiler is the same unit found on the Bullitt Mustang. Installing a Cobra hood presented a minor challenge, though, because it's shorter than the GT unit, so Mike added some material at the fascia using urethane body filler, which filled in the gap for a more sculptured look. He also did away with the stock honey-comb grille for better airflow and a cleaner look by using an eliminator kit from Classic Design.

Before showing up at the next Power Tour, the car's greatly improved performance required some proof on the track. At Road Atlanta, Mike attended the Year One Challenge, where he reeled in a hot-rodded Camaro and Panoz in short order. "It was snowing, and they pulled over to let me pass," Mike says. "The Camaro couldn't keep up, and the Panoz was braking 300 feet before the turns, while the Mustang did it at 200 feet." Afterwards, the course instructor who had been driving the Panoz asked Mike, "Have you been doing this awhile?"