They are most commonly known as “Purple Crack.” They are addictive, but for some people, the cost is enough to break the addiction.
The closest I ever was to matching Hoosier times with street tires, was about 1.5 seconds (behind) on a 40 second course. While they might get you faster times, they won’t make you a better driver. If you’re just out for fun, the Hoosiers are hard to beat. If you’re out to become a better driver, you might want to stick with street tires. Not that I want to talk you out of buying Hoosiers 🙂