LED Running lights....ICYMI.
I replaced the running lights and brake lights on my 2109 Mini-Lite and wasn't real happy with the brightness. However I learned here that by adding metal tape, to the inside back that is black plastic, provides a reflective quality, and it significantly increases the brightness. Simple effective fix, especially if you have the tape. You could probably use the white part of the red and white reflective marking tape if you have that. It doesn't have to be pretty to be effective as it is covered by the lens.