I've spent a few hundred dollars recently on various equipment, trying to get a usable secondary ignition waveform from a Subaru coil over plug design, only to finally end with this capture from an AESWAVE paddle probe. Perfectly running 2012 Impreza.
After a brief chat with the guys at Aeswave about it, they did some research that even I, as a Subaru dealer tech, could not find out without contacting a field engineer. Any 3-wire coil over plug design you find on a Subaru will have an ignition module inside it, and that's the pattern I'm getting. The coil windings are too well shielded and the module is closer to the probe than the windings ever could be, so this pattern that I'm getting on all subaru coils is actually coming from the module and not the windings.
Now I need to go find an extension plug wire that actually works and isn't Hantek crap.