Originally Posted by stlwagon
Just reflash the car to stock, no need to remove the battery cable (and certainly not the ground). They'll be able to tell it's been flashed, but not who did it.
The following is from another forum:
"Been a tech for Ford for last 14 years.
There is no way we can tell if the tune has been changed.
Resetting, over rev, and speed limit reached are stored, but can be erased just by disconnecting the battery for
If asked why the battery was disconnected, just say you left the dome light on, and had to get the battery
We can't prove otherwise."