Added 2 12V Piezo electric buzzers in the turne signal circuit. First I spliced into the turn signal indicator lights at the connector. To release the connector from the plastic part, you use a small jewelers standard screwdriver to depress the little spring tab that locks it in, then you can remove it from the block and solder a small jumper wire in place, do this with the black and the green wires.
I chose to complete the circuit by grounding in the mounting screw from the coil and mount the buzzers in place with a spot of clear silicone.
You cannot feed both circuits into a common buzzer or they backfeed the other circuit and look like hazard flashers. You could use a single buzzer unit if you used diodes just before the buzzer to prevent backfeed, but two buzzers were cheaper than 1 buzzer and 2 diodes.
Evaluation:
Works well at lower speeds, but when accelerating away from a turn, they are somewhat hard to hear. I think either a louder buzzer - I am looking at ones from Allied Electronics, or I am also going to try a pair of 12V LED bars I got from Walliworld that are bendable and would attach to the edges of my windscreen. They should flash just like the cluster lights.