A GTRs could be configured with engines in a number of different guises. In some cases, the C5’s 350-horsepower LS1 V8 was left alone, though the standard GTR conversion kit included some carbon-fiber engine-bay bling (air-filter lid, fuel-rail covers and fuse-box lid) and a stainless-steel Corsa exhaust system. Additional output came in the form of five engine upgrade packages, as well as the option for custom mods. The top normally aspirated V8, the PowerWerkes Matrix Three, was ostensibly a 7.0-liter race engine; it cranked out over 600 horsepower and cost a whopping $23,895. The 750-bhp PowerWerkes Matrix Three Vortex Supercharger kit cost even more, nearly $30K.
At $9,645 installed, the PowerWerkes Supercharger option offered the most bang for the buck. It included a Magnusson Supercharger, which boosted output by 100 ponies, and required an aggressive-looking Power Dome hood ($1,295) to make room for the top-mounted blower. This is the option that Purifoy selected for its 50th Anniversary coupe, but it had Specter perform a few internal engine mods, as well, including the installation of a Z06-spec LS6 camshaft, ported and polished LS6 cylinder heads and larger (2.02-inch) intake valves. This off-the-menu request cost $4,200. Combined with Specter’s GTR PowerWerkes Headers ($895), these mods swelled the small-block V8’s output to 555 horsepower.
All of this work was done at the Specter Werkes/Sports shop in Troy, Michigan. In most cases, untitled Corvettes were sent there directly from the Bowling Green Assembly Plant—GM had given the GTR project its blessing. They were built according to the specifications requested by either Purifoy or Cauley, which then displayed them for sale on their showroom floors.
With the sun dipping low over the horizon and my photos in the bag, I slide into the GTR’s low-slung cockpit to get a feel for it on the road. The blown LS1 comes to life with a subdued rumble. Rev it, and the Corsa exhaust system emits great music—not obnoxiously loud yet extremely powerful. Most of the controls, from the clutch to the steering, are as light and pleasant to use as those in a factory stocker. However, the B&M short-shift kit reduces fore-and aft as well as side-to-side motion considerably over a standard shifter—so much so that it takes a minute to get used to. To be honest, I accidentally drove off in third gear, though I hardly noticed thanks to the engine’s deep well of low-rpm torque.
Dipping into the throttle changes the GTR’s pussy cat-like demeanor at lower speeds into that of a roaring tiger. The resulting acceleration is impressive, but the car doesn’t feel gut-wrenchingly fast. That’s because the torque curve is as flat as can be and there are no spikes in the powerband. The engine revs smoothly and eagerly right up to redline without complaint or a drop-off in power. With the supercharger adding a subtle whistle to the exhaust note, the GTR simply hammers down the road with authority.
The car’s handling is commendably neutral. The chassis responds quickly and accurately to steering inputs. There is a hint of body roll on initial turn-in, but the GTR corners confidently, with the front tires gripping obediently and the back following right around. Despite the extra stick afforded by the wide rubber, the stiffer sway bars do make the car feel a bit more tossable than a standard C5, and the Baer brakes slow the car from the triple-digit speeds with ease.
Dave loves the GTR’s performance, but its not his favorite aspect of the car. When pressed about what he likes most, his answer comes without hesitation: “The appearance. Both the interior and exterior are really well done. The Anniversary Red has a great ‘pop’ to it that is nicely complemented by the bodywork. The interior takes the 50th style cues and improves on them to make a beautiful combination of colors.” The Amblers wanted a special 50th Anniversary Corvette and they got it.