If your compression is too high, or timing to advanced then it will pink.
Pinking is also known as knocking. You will hear it most at high revs or under load. If you can hear it without the knocking ear muffs then it is pretty bad.
We get 98 here. My 2l will pink on anything lower octane on the settings I have it.
It is really hardsh on bottom end and will/can also melt your pistons.