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Here's an article from Popular Mechanics.
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April 29, 2008

2008 Mustang Shelby GT500KR Test Drive: Does Ford’s 540-hp Monster Live Up to Limited-Edition Hype?
Mustang Shelby GT500KR

SALT LAKE CITY — Say what you will, but the association between Carroll Shelby and Ford’s Mustang has been a long and profitable one. Now the 2008 Shelby GT500KR marks the newest flagship in that 40-year run of limited-edition iconic rides, with 1750 units headed to production at a fairly staggering $79,995—and that’s before dealer premiums. But it will be the most powerful Mustang ever to hit the dealership. We wondered which of the Shelby faithful would subject his $80,000 toy to the rigors of a track day near here on the West Loop of Miller Motorsports Park’s impressive facility—and found out that it wasn’t likely to be many. —Barry Winfield

The Specs
By most powerful we’re talking a 540-hp supercharged 5.4-liter V8, with max torque upped by 30 lb-ft. to 510. Most of that performance increase comes from a new cold-air inlet system isolated at the front of the engine bay under an elaborate new carbon-fiber hood, and from revised engine-control calibrations.

The power increase is abetted by a shorter rear-axle ratio (3.73:1), and the combination produces sprints to 60 mph in 4.3 seconds, and quarter-mile times of 12.1 seconds, according to Ford’s SVT performance engineering division. Accompanying the invigorated drivetrain is a thoroughly revised chassis. Spring rates were increased 17 percent in the front and 7 percent in the rear, while anti-rollbar rates were slightly reduced.

In the process of recalibrating the chassis, all-new shock valving was developed for the Tokico dampers fore and aft, and the front axle’s geometry was revised to increase the camber and set the toe to zero. The SVT team insists that some of the suspension changes were demanded by the car’s revised aerodynamics. Because SVT wanted better front-end stability, they fitted a prominent carbon-fiber splitter to the restyled nose, moving the center of pressure nearer the front, and closer to the car’s center of gravity.

Despite the mini tail spoiler seen on the new KR, rear downforce was actually reduced. The result, says SVT, is a more balanced vehicle. The final step was to persuade the tire suppliers at Goodyear to find a new tread compound for the 18-in. Eagle F1 rubber. Actual wheel and tire sizes remain the same as on the Mustang GT500, at 255/45ZR18 front and 285/40ZR-18 rear, but a small winged-foot emblem on the sidewall signals the stickier formulation, along with a lower wear rating.

Now with unique handling characteristics, the KR required a different set of ABS calibrations to put the 14-in. Brembo brakes and four-piston calipers to best use. So the engineers revised those control algorithms, too. In keeping with its overtly sporty appearance and performance, the KR is fitted with a short-action gearshift mechanism, which increases the effort required to shift gears, but abbreviates the movement necessary to do so. The stubby gear lever is topped with a perfectly simple white ball.

The Drive
Before testing the new GT500KR, we expected most aspects of its conduct to be somewhat hefty in nature. But in truth, only the clutch and shifter have manly weighting. The ride is surprisingly compliant for such a well tied-down heavyweight (3900 pounds), and the steering effort has entirely tolerable levels of effort.

So steering the car isn’t a problem, but driving it really smoothly in stop-and go conditions isn’t as easy, since the clutch take-up is hard to finesse with the strong return pressure urging your foot off the pedal. Once you’re underway, the KR smooths out somewhat, and you can begin to appreciate the muscular engine—not to mention the Shelby’s muscular exhaust note (a deep, staccato bark) and the supercharger scream (muted but manic).

There’s plenty of torque at low revs, and thus no real need