C63 is an over-achiever much the same way the ZL1 is an underachiever.
Bolt-ons + a tune make a lot of power in those things. A few guys are running 10's all motor in those things (sedans too). I've done a lot of research on these as I would probably be buying one if the 13 GT500 didn't perform so well.
Which is a more comfortable, a ZL1 or C63? LOL
Edit - C63 weighs ~3900 lbs, lighter than the ZL1.