Because the package costs more than a Shelby GT500.
Hennessey Performance Engineering may be best-known for its high-output tuning packages for all-American performance vehicles like the Ford Mustang and Chevrolet Corvette, but the company isn't averse to fiddling with products from other countries, too. As a matter of fact, the Texas-based tuning outfit has had a go with the Audi R8 V10, and what they've come up with is quite spectacular: a 912-horsepower "HPE900" package that sees the factory ten-cylinder bolstered by a pair of turbochargers.
The result of this extra power is a stated 0-to-60-mph sprint time of just 2.6 seconds, and a blistering 9.8-second quarter-mile at an ungodly 145 mph.
That earth-shattering straight-line performance is achieved through a high-flow induction system feeding into a pair of Precision ball-bearing turbos and dual air-to-water intercoolers. The factory exhaust is ditched in favor of a custom thermal-coated stainless steel system with thermal-coated downpipes - a nice touch given that hot gases are faster-moving gases, and faster-moving gases get the turbos spooling faster.
Although they don't help performance any, interior and engine plaques, and a selection of exterior Hennessey and "Twin Turbo" badges, are tossed in for good measure. The engine calibration, dyno testing, and up to 200 miles of road testing are all performed by Hennessey's seasoned tuning pros, and the package comes with a 1-year/12,000-mile limited warranty.
And there's further good news, too: because the Audi R8 V10 is so closely related to the Lamborghini Huracan, especially in the powertrain department, the same HPE900 package can be had on that car, as well, and similar gains can be expected.
The bad news? The package costs a whopping $79,500 installed. Which is, you know, rather a lot. More than a standard C8 Corvette, and more than a contented Mustang GT500, for example.
Then again, we'd challenge you to find another shop with Hennessey's reputation to twin-turbo your Audi R8 or Lamborghini Huracan for less. Performance comes at a cost, especially when the base car is a high-priced European exotic.