When it comes to driving a late-model GTO, what true performance enthusiast doesn’t get excited about a rear-wheel-driven, two-door coupe with a 400hp V-8 nestled under the hood? Gary Powers of Allen, Texas, certainly did.
As chief information officer at a local bank, the 39-year-old admits he has always been interested in late-model performance. “I like all vehicles of all types and bought a ’98 Jeep Grand Cherokee Limited with a 5.9L that I mildly modified and raced, and it was pretty fast. That’s when I started noticing how well the new LS1-powered Firebirds and Camaros were running on the dragstrip, especially with very mild modifications.”
The boosted LS2 exhales through...
The boosted LS2 exhales through 1.875-inch-diameter ARH headers and a 2.5-inch MagnaFlow after-cat exhaust system. BC Racing coilover springs up front and rear give the GTO the desired stance. Housed within a floating axle housing is a Detroit TruTrac differential and 3.73 gears.
When the GTO debuted for ’04, it was powered by a 350hp LS1, and Gary had the opportunity to testdrive one. “I thought it looked great, and was impressed with its performance and build quality. When the ’05 GTO came out, the 400hp LS2 engine and dual-scooped hood made it even better. I knew LS engines had great potential to create very high horsepower and the aftermarket was loaded with performance components, so I started thinking about getting one.”
In the summer of 2008, Gary’s wife spied an ’06 GTO for sale on her corporate classified listing. “It belonged to her friend’s husband and she asked me if I was interested,” he says, “He was selling it to purchase a Mercedes, and it was in excellent condition with just 21,000 miles on it. I loved the Impulse Blue exterior color and it had a six-speed. It was exactly what I was looking for.”
Acrylic Conceptions provided...
Acrylic Conceptions provided the data plates that Gary installed on the center console.
Gary made arrangements to take a closer look. “When I saw it for the first time I immediately said to myself this is my next car,” he recalls. “It was absolutely gorgeous. The testdrive was very impressive too. The owner took me out and showed me what the LS2 was capable of.”
Whiteside Customs added its...
Whiteside Customs added its Lightweight mesh-style wheels in 18x8.5 inch (front) and 18x9 inch (rear), which are powdercoated black and feature a painted blue lip. Nitto 555 tires in 245/40R18 are used up front, while Nitto 555R Drag Radials in 285/35R18 are used at rear. Drilled and slotted brake rotors are from Baer, while the original GTO calipers were painted blue.
When making the purchase, Gary knew he would soon modify his new GTO. “I was very impressed with aftermarket support toward the LS engines and how buildable they are. I installed a few components to capitalize on the stock potential. That included a cold-air induction kit, an aftermarket exhaust system, and better tires. I was pleased with its performance but dreamed of someday adding a supercharger. I wanted to first grow accustomed to a 400hp LS2 backed by a six-speed manual before taking the next step, however.”
Within a year Gary began selecting a supercharger package for his GTO. As a member of LS2GTO.com, he learned that a roots-type supercharger provides several advantages, and among the most important to him was that it fit under the GTO’s stock hood line.
East Texas Muscle Cars (ETMC) is a popular GM tuner located in Longview, Texas, and Gary learned of it from the GTO forum. “I contacted ETMC and explained that I wanted to increase performance by adding a supercharger, but wanted to retain maximum reliability so I could drive the GTO daily. The staff suggested a Magnuson TVS 1900 supercharger, an air-to-liquid intercooler, a ported throttle body, tubular headers, and a performance exhaust system. We hoped to see an increase of 150 hp at the rear tires, but it was actually closer to 200!”
The GTO’s black leather interior...
The GTO’s black leather interior is largely unmodified. The T56 six-speed manual transmission is controlled by a B&M Ripper shifter. A Hendrix Stage 3 clutch and pressure-plate assembly channels power from the engine to the transmission. A Kenwood stereo with navigation replaces the original.
Gary made arrangements to leave his GTO with ETMC for a few weeks while the installation—which also included upgrading GM’s “243” heads with Patriot Extreme dual valvesprings and Comp 7.400-inch-length hardened pushrods, and swapping out the factory driveshaft for a two-piece, 1,000hp-capable unit from The Driveshaft Shop—was performed. The modified LS2 was then performance tested on ETMC’s in-house Dynojet chassis dyno, where it generated an astounding 528 rwhp at 6,400 rpm and 497 rwtq at 4,100 rpm on 8 psi of boost. When factoring the driveline loss, Gary tells HPP that it equates to roughly 620 hp and 575 lb-ft at the crank.
With more than 600 hp on tap, Gary says of his GTO, “It was extremely fast, and beyond the well-hidden intercooler, the exterior otherwise looked bone-stock. After a year I decided that I wanted a slightly more aggressive appearance, and that’s when I talked to Mike White at Whiteside Customs in McKinney, Texas.”
At the center of the dashpad,...
At the center of the dashpad, just above the center ventilation outlets, is an aftermarket gauge pod that houses Stewart-Warner boost and voltage gauges.
Mike felt that stripe packages were generally overstated, and that a set of new wheels and some mild suspension modifications would enhance the GTO’s stance, giving Gary the look he was after. “We took inspiration from the exotic-car world and installed black wheels with a blue-painted lip,” Gary explains. “Mike also installed new coilover springs, and replaced the original suspension bushings with urethane units.
“I really like the new look,” he continues. “It’s very menacing without being overdone. I love having a daily driver with more than 600 hp. Cartoon-like acceleration is a throttle stab away, but you would never guess that from looking it. This GTO is very unassuming.”
The 400hp LS2 bottom-end remains...
The 400hp LS2 bottom-end remains factory-stock, but East Texas Muscle Cars installed a Magnuson TVS 1900 supercharger, intercooler, and Magnavolt fuel system; a Lingenfelter CAI kit, 42-lb/hr fuel injectors, and some severe-duty valvetrain components. With a canned Magnuson computer tune, and 8 psi of boost, it generated 528 hp and 497 lb-ft at the rear tires.
Gary enjoys taking his GTO to the dragstrip. “I will only run DOT-approved drag radials. I’d rather give up some traction instead of breaking parts. It has run the quarter-mile in 11.9 seconds at 114 mph in the Texas heat, but it has the power to be in the mid-to-low 11s. I’m hoping to see that when the weather cools down.”
Beyond additional visits to the dragstrip looking for reduced e.t.’s, Gary says he has no immediate plans to further modify the GTO. “I’m very happy with its looks and performance and don’t feel the need to change a thing. If I ever feel that a power increase is in order, I can install a supercharger-spec cam and a smaller diameter supercharger pulley, and add another 50 to 80 hp, taking the total toward 700.” Now that’s exciting.