No not really Willow. You don't even need any tools, as the nearest terminal (the negative (black)) has a quick release clip on it, you just undo it (it's surprisingly large), and set it aside away from the terminal for a while.
You will need to reset the clock on the main menu, and you'll lose your trip computer data.
Bear in mind that these ECUs are "learning" (not really learning like a Cyberdine T-101!) processors, they monitor all sorts of sensor parameters like fuel usage and pinking (or lack thereof) over time and then after set periods of measurement make adjustments to things like ignition timing. This may explain why the mod seems to "wear off". Disconnecting the battery will wipe the sensor data in the ECU (plus your clock and trip computer), and thus the ECU reverts to whatever "map" data it was last flashed with - and this will include any mods you've had.
Brat Pack no.8