Honestly, the 100 HP/liter is only impressive if the engine is not using forced induction. Pretty much anybody can get 100 HP/liter with a blower or turbo set up.
Ummm...pretty much anybody can do it naturally aspirated if they spend enough money. The catch is that anyone can do it a lot cheaper with a blower or turbo, that's all. Do you know how much the new Z06 costs? The PRICE is certainly impressive, but nobody has really achieved anything impressive by buying something that most other people cant afford.