Naturally Aspirated
With the willing, 400-horse LS2-which retains elements of the previous LS6 engine, including the cylinder heads-as a starting point, the Group 6's engine was treated to Specter Werkes' "Matrix 1" makeover, which included a special-grind camshaft, CNC-ported cylinder heads (with larger valves), a Lingenfelter cold-air box, LG Motorsports long-tube headers (with 3-inch X-pipe) blowing into a Corsa exhaust system, and a pan full of Mobil 1 oil. It's a relatively simple combination that, while requiring some careful tuning for optimal performance, delivers 525 hp and 435 lb-ft of torque.

This is race-car horsepower and time-warping torque. Besides the output, however, is the Group 6's rumble and idle quality. It barks to life with a raspy growl, thanks to the long-tubes and Corsa pipes, but it settles into a thumping, low-rpm idle that instantly reminds us of the solid-lifter days of yore. The moment you hear it, you think one thing: "Man, that thing's got some cam." With 500-plus horsepower, the Group 6 has no trouble hazing the nubs off the new Michelin PS2s. Throttle response is more immediate, too, thanks to a few well-placed taps of the laptop keyboard.

Surprisingly, all this power is channeled through an otherwise stock drivetrain. The cooling system is stock, and so are the six-speed manual transmission and clutch.

"All the factory parts are more than adequate for the power," says Nowicki.

Those with a stronger need for speed can order up a stroked Matrix II powerplant, a 7.0-liter C5-R-derived engine, and a Matrix SC engine equipped with a MagnaCharger blower. These upgrades ain't exactly cheap, but as the axiom goes, speed costs.

The full Group 6 treatment also encompasses suspension and brake enhancements, including Stop Tech ST-60 brakes with six-piston front calipers and four-piston rear calipers clamping down on drilled rotors-including huge 330mm (13-inch) units up front. The suspension receives the T-1 upgrade kit from GM, which includes new front and rear springs, stabilizer bars, upper and lower front A-arms, and stronger links.

Inner Style
Along with the exterior and performance upgrades, the Group 6 package also includes a sumptuous upholstery upgrade, with Spinneybeck Italian suede. The burgundy-color material, embroidered with the Group 6 emblem on the headrests, adds a decidedly upscale aura to the Corvette's cabin, complementing the 525 hp in true velvet-hammer form.

All told, the exterior, interior, and performance enhancements of the Group 6-including installation, tuning, and paintwork-run about $30,000. Even with a brand-new Corvette, that's not much more than the cost of a new Z06. There's also the intangible quality of exclusivity-not too many other enthusiasts will have one.

What we really like about the Group 6 lineup, however, is the cafeteria-style options menu. Don't like the extractor hood? Leave it off. Want everything but the T-1 suspension? No problem.

"It is first and foremost the customer's car," says Nowicki. "He tells us how to build it."

While the quantifiable traits of the Group 6-such as the Matrix I engine's dyno numbers or the skidpad performance of the T-1 suspension and Michelin PS2 tires-are easily justified, the intangible traits are the package's real strengths. The hunkered-down stance, just-try-me idle quality, and race-ready form are simultaneously unmistakable and understated.

For those who appreciate such a design philosophy, the Group 6 backs up its form with searing function.