Actually, that gizmo is surprisingly accurate. If you key in 3150lb and 13.3s (Road&Track's 1/4mi time), it says 264hp, which is right on the money. To get to 12s it says you'd need 365hp or so, which is 410 FWHP. To get this you will need a well-tuned X51 or forced induction. Or, more economically, trade the CS for a C6.