A project Pontiac can have many directions in its lifetime, but not this feature story's 2004 GTO. From its present owner's start with it, the single goal was to make a high-horsepower monster that prowls the streets and the track. Like a wolf in sheep's...make that goat's clothing, it may look fairly stock, but don't let its docile appearance fool you. This Pontiac has some serious teeth under the hood.

"I wanted the GTO because it would be a nice, safe, and comfortable vehicle to drive," says Chuck Stefanski, owner of Big 3 Racing in Hinkley, Ohio. He scored his black-on-black LS1/six-speed coupe for the sweet steal of $9,000. "It had 100,000 miles on the odometer, but it was bone-stock and in need of some freshening."

By freshening, Chuck meant turning his GTO into a 800-plus-horsepower, tire-roasting tiger.

First up, he plumbed a custom, direct-port nitrous system using Dynotune solenoids capable of delivering a 200hp hit of giggle juice into the LS1's stock intake. Then it was heads, cam, and exhaust—ported "241" factory castings, a Texas Speed Torquer V2 bumpstick (232-/234-degrees duration/113-degree LSA), Pacesetter headers, and Flowmaster pipes—to open the GTO's lungs.

He describes nitrous as "a novelty that soon wore off," but his need for speed was insatiable. So out came the nitrous plumbing and in went a custom turbo system, featuring a 76mm Precision turbo and custom stainless-steel headers. Strapped to the dyno, the Fifth-Gen Goat put 570 hp and 632 lb-ft through the stock bottom-end on pump gas.

All of that power was great, but after one too many trips down the track and spirited driving sessions, the stock aluminum block waved the white flag and surrendered. "It was time for the build to get serious," he says.

For Chuck, serious is defined as a bulletproof, boost-friendly, reliable combo. That's what's in his GTO today. It starts with a 364ci/6.0L LQ4 iron-block, stuffed with an Eagle 4.000-inch-stroke crank that swings -10cc-dished Mahle aluminum pistons on a set of Eagle H-beam rods. The final displacement checks in at a stout 408 cubes.

A set of heavily ported GM "317" casting heads with 76cc combustion chambers supervise the block. An upgraded valvetrain packing 1.6:1 Jesel rocker arms matched to PAC 0.650-inch-lift valvesprings and custom Trickflow pushrods keep the top end synchronized, and a custom-grind cam (231-/238-degrees duration/115-degree LSA) orchestrates the system.

In the air, fuel, and oiling departments, most of the stock components were all upgraded. An 80mm Trickflow throttle body forces a battalion of boosted air through a GM intake and into the gullet of the mill. A Holly Dominator fuel pump, an Aeromotive regulator, and Trickflow 80-lb/hr injectors mean it's always feeding time for the growling tiger. A Melling high-volume oil pump keeps the powerplant lubricated.

Big 3 Racing's in-house–fabricated turbo system serves the Goat the aforementioned boost. It starts with a custom-built 76mm Precision turbo that dumps to a 3.5-inch downpipe. Big 3's fabricated turbo headers (1.75-inch primaries/2.5-inch collectors) exhume the exhaust gas to a custom 3.5-inch aluminum exhaust and Vibrant Aluminum muffler, which gives the Goat a killer exhaust growl.

On nice days, Chuck's GTO sees heavy street duty, so he added a Treadstone 4-inch-core, front-mount intercooler to keep the air as cool as his ride looks. (This intercooler is rated up to 1,400 hp, so Chuck has room to turn the boost dial past the current 15 pounds.) A Tial wastegate and BOV keep the tiger's condensed air molecules in check and flowing without interruption.

A billet-steel Mcleod flywheel and Street twin clutch pass the ponies to a stock T56 six-speed manual transmission, and then through a Driveshaft Shop aluminum driveshaft to a factory-stock independent rear suspension. On pump gas and 15 pounds of boost, this spirited pass-hauler puts down an asphalt-melting 800 hp and 816 lb-ft of torque.

Like many GTO owners of the '60s, Chuck cares more about getting his GTO down the dragstrip in a straight line than corner-carving around cones or winding road courses. "Power, power, power," he says. He added a set of BMR airbags, which helps him hook off the line on TSW Indy 500 wheels wrapped in 265/40/18 M/T Drag Radials. When its time to bring his mighty GTO to a controlled stop, factory calipers with Powerstop pads bite down on drilled-and-slotted Powerstop rotors.

This gargantuan-powered GTO is no stranger to the track, and it is often called upon to combat in the LSX Challenge series, competing in both EFI Rumble and True Street classes. At over 4,100 pounds in full street trim, its 11.18 e.t.'s at 140 mph are impressive.

Over the years, Chuck has owned many different cars, but he's hit a home run with this GTO. By taking a platform that is easy to modify, he has created a beastly street car. So if you're ever looking for a race and you see this Pontiac, you better think twice. This monster of a GTO has some big teeth and knows how to use them.