There seem to be two diffusers there - the carbon one looks awesome and I reckon it does something, the other looks a little like a stick-on with no real benefit.
Unfortunately, I have the Tequipment Sports exhaust so both are a no-go. But I do have the smoked light:
Initially it didn't work, so I had to reverse the polarity. This is easiest done by pulling the rubber grommet out that holds the power cable for the brake light, nipping the cable, adding bullet connectors and swapping them over, and then put back the rubber so nothings visible, and voila.