If you passionately love what you do, you'd work for free. That's the old adage, and that's apparently what a bunch of Ford Mustang engineers did in order to develop their dream Mustang chassis/handling package. These track enthusiasts had a vision of their ideal Mustang that went beyond the Performance package that got baked into the initial 2018 Mustang order book. Rather than ask permission and risk being shot down, this internal skunkworks toiled nights and weekends developing the parts needed to achieve their own aggressive targets. As soon as the package suited them, they presented the results to their bosses, and voila! Now we can all enjoy an even more extreme Performance package variant for the 2018 Mustang GT dubbed simply "Level 2."

First, a refresher on the preapproved Performance package. For $3,995, the GT Performance package adds: 9.0-by-19 front and 9.5-by-19-inch rear black wheels wrapped in 255/40R19 and 275/40R19 summer tires, respectively, Brembo six-piston front brake calipers with larger rotors, oil pressure, and vacuum gauges, heavy-duty front springs, a stiffer rear anti-roll bar, an underbody K-brace, a larger radiator, performance rear wing (fastbacks) or spoiler delete (convertibles), silver-painted strut-tower brace, Torsen differential with 3.73:1 axle ratio (manual) or 3.55:1 axle ratio (automatic—sorry, Level 2 is available only with the manual) and unique tuning of the chassis/electric power steering/ABS/stability-control systems, and Magneride adjustable dampers. You know, like the ones used on various Ferraris, Corvettes, and the Camaro SS 1LE package. Think of Ford's base Perf Pack as roughly equivalent to a Camaro SS ordered with the 1LE handling and Magnetic Ride packages, which together cost $3,665.

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Perf Pack Level 2 is a $6,500 package available only on Mustang GT fastback manual cars. If ordered on a base GT, you must also opt for the $2,000 Equipment Group 301A—dual climate control and Sync 3 AM/FM/CD, and for comparison purposes against Chevy's full-on $7,000 1LE Track Performance package, you might as well know that Level 2 lacks the 1LE's head-up display, and Ford charges $895 for its performance exhaust that Chevy throws in.

Level 2 aims to counter the dynamic capabilities of the 1LE Track Pack. To do so, the skunkworkers took a holistic approach to enhancing mechanical grip and aerodynamic downforce. For starters, there's a good bit more rubber meeting the road: The tire cross section is increased considerably by fitting 305/30R19 meats all around, mounted to staggered-fitment wheels that are 10.5 inches wide in front and 11.0 inches in back. Oh, and naturally they're not just any old tires—they're Michelin Pilot Sport Cup 2s (Camaro SS 1LEs we've tested ran Goodyear Eagle F1 Supercar 3 tires, 285/30R20s front, 305/30R20s rear).

Working our way up, relative to the already stiffened Perf Pack springs, the Level 2 coils are 20 percent stiffer in front and 13 percent stiffer in the rear. Similarly, the anti-roll bars resist twist by an additional 12 percent in front and 67 percent in the rear. Oh, and between the lower-profile tires and suspension tweaks, the car hunkers down a half-inch closer to the road. Some of the midnight oil burning involved further tweaking of the Magneride shocks, electric steering assist, ABS, and stability control tuning.

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The aero work started off with a modified Boss 302 Laguna Seca front splitter that extends about 3 inches out from the front corners, developing 24 pounds of honest-ta-goodness front downforce at fast-sweeper speeds (80 mph). Balancing this out is a subtly redesigned rear spoiler that was designed by a process of successive track tests with different designs that had been 3-D printed.

The end result is said to roughly split the track performance difference between the GT Perf Pack and the mighty GT350, delivering lightning-quick responsiveness and seemingly endless braking and cornering grip. You'll be able to spot a Performance Pack Level 2 car by its unique 10-spoke "Dark Tarnish" wheels, black spoiler and splitter, and tire spats on the back of the rear wheel openings.

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See all 14 photos