Pinging=detonation
It's caused when the timing (fuel/air) is too far advanced...it creates an un-even burn in the cylinder, and it can cause pitting on the surface of the pistons.
If you want to advance the timing, make sure you use PULP to get the most out of it.
There's no need to put the car on a dyno to advance the timing, go buy a timing light and do it yourself.... check what it's set at, advance it a few degrees, go for a drive.. if it doesn't ping, advance it a bit more...
...but as megs said, if it starts to ping, back it off.