Power routes through an Exedy carbon-fiber clutch to a G-Force T56 six-speed transmission. The stock 3.31 gears are still in the car, though Mark Williams halfshafts direct power to the Pilot Sports. Each corner is fitted with Baer Extreme-Plus 6R six-pot brakes, a good idea when you have this much power under your right foot.

The GMS Z06 doesn't exactly look tame, thanks to its flamed paint, Classic Design Concepts Tiger Shark front and rear fascias, RKSport carbon-fiber hood, and Catz HID conversion. Yet it can be surprisingly docile when you resist the urge to stand on it. In putt-putt mode, about the only tip-off to the car's potential is the whine from the T56's straight-cut gears.

As we idled down the freeway on our way to the photo location, J.R. was happy to show us, via the Corvette's onboard computer, that it'll return respectable mpg if you behave. (Yes, it felt odd to talk about fuel economy in the context of a street Vette that'll turn the quarter-mile in less than 10 seconds, but it's a hard topic to avoid these days.) He was well on his way to achieving 20-plus mpg until we asked for burnouts for the camera. "Those burnouts just did us in," he said later, pointing at the 14.1-mpg reading above the steering wheel.

That ain't bad, especially since our burnouts weren't entirely to blame for the dip in fuel economy. On the way to our shoot, J.R. couldn't resist giving us a taste of just what this Vette can do. Stomping the accelerator is a traction-avoidance maneuver that'll just vaporize the tires. But when J.R. leaned into the pedal, the surge to speed felt like a meaty hand shoving us back into the seat, while the needles in the dash tracked not just engine and road speed but our own adrenaline spike. Just as quickly, the big Baers hauled us down to match the flow of traffic, and we had a chance to catch our breath.

So, do customers ever ask for more than this? we asked.

J.R. smiled. "No."

Spec Sheet
Car:'04 Z06 Corvette
Owner:Granatelli Motor Sports
Block:GM LS6 with Darton sleeves
Displacement:427 cubic inches
Compression Ratio:8.8:1
Heads:GM LS6, ported to Stage 5
by Motorsport Technologies
Valves:Manley,2.05/1.62-in
Camshaft:Cam Motion
RockerArms:Granatelli rail-mount rockers
Pistons:Ross
Crankshaft:Lunati
Rods:Lunati
Intake Manifold:FAST
Throttle Body:GMS-modified LS2
Fuel Injectors:ACCEL 55-lb/hr
Fuel Pump:Twin Bosch 930 Turbopumps
Ignition:Stock with Granatelli 0-ohm wires
Engine Management:Stock, tuned by Granatelli
Motor Sports with EFI Live
Power Adder:Granatelli Twin Turbo Kit with
twin 76mm ball-bearing turbos
Maximum Boost:12psi
Intercooler:Granatelli/TTI Mega-Cool with
twin TTI induction fans
Exhaust System:Granatelli exhaust with Corsa mufflers
Transmission:G-Force T56
Clutch:Exedy carbon fiber
Driveshaft:Stock
Front Suspension:Stock
Rear Suspension:Stock
Rear End:Stock w/ Mark Williams halfshafts
Front Brakes:Baer Extreme-Plus 6R w/ six-piston calipers
Rear Brakes:Baer Extreme-Plus 6R w/ six-piston calipers
Wheels:HREGranatelli Signature Series
Front Tires:Michelin Pilot Sport 275/40ZR-19
Rear Tires:Michelin Pilot Sport 345/35ZR-19
Fuel Octane:91
Weight:3,125lbs
Best ET/MPH: 9.76 at 154mph (spinning)
Best 60-ft.Time:1.41
Current Mileage:824
Miles per Week:"Could be driven daily, but I just take people for rides."