To me a 'sleeper' is more about how the car looks and sounds.
Anything you want can be hiding under the hood if the car looks somewhat sedate and has a nicely-muffled exhaust.
If you're out doing a little stoplight to stoplight fun, who sees under the hood anyway?
This was a fun little sleeper, 455 with Tri-Power, essentially stock but still had enough power to surprise a lot of cars that challenged it.
