It's true, the Cobra and Corvette are in different classes on purpose. Actually, after having attended a few road racing events, the Corvette guys don't even pay attention to the Mustangs. They tend to consider cars like Porsches their main rivals.
As for power, I can buy a brand new Cobra for much less than a Z-06, spend $500 and 3 hours installing a nitrous kit, and keep up with him, if not beat him. Not a bad deal, especially when I see the look on the other guy's face.
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Moxie Racing
The Nitrous Oxide Information Site