Heffner has finally wrapped up work on the company’s wicked twin-turbo R8. The guys are currently running just 6 psi to keep things from going kaboon, but even at that low pressure this beast is developing a whopping 536 horsepower – at the rear wheels. Once the guys get comfortable with what the car can do, they plan on running race fuel to up the grunt closer to 600 horses. Just for reference, the bone-stock 4.2-liter V8 dishes out 420 horsepower. Hop the jump to check out the car as it blasts from second gear to forth. [Source: GermanCarBlog]