I literally went to my installer today about this, after taking it to the service center (worried that it was an upper control arm issue). Both the service center and installer agreed that it was likely spring binding, which apparently is a relatively common issue with aftermarket springs. How it was explained to me: as a spring compresses, it twists or rotates. If the spring isn't allowed to rotate as it compresses for whatever reason, it can skip and cause that pinging noise. Not really a safety issue and maybe a performance issue if you're racing (but not a concern for street use).
@MountainPass correct me if I'm wrong with this explanation.
Installer said they would reach out to MPP about it to see if they have any advice. Otherwise, they would install thrust washers (or bearings), which allow the springs to rotate more freely as they compress.
Others with more knowledge of aftermarket suspension can chime in, as I'm just relaying info that was given to me by the service tech (shout out to Dustin at the Lisle, IL SC), and my coilover installers.