I have only run into one, that I know was somewhat modded (exhaust+intake+?), and we were door and door from 70-140 on 3 tries. The Z06 was quick. I figured I would have gotten murdered 0-70. Remeber, just because both cars make similar hp (say ~400) and weigh similar (Z is heavier than Z06), the Z06 is non-turbo-meaning the HP curve is basically flat (or close to it); meaning the Z06 is going to get a jump on you at the line (most of the times-drivers being equal). This means if you are racing from a stop, your car needs more HP to win (drivers being equal).