My original prototype uses different LEDs(about half the MCD) and the 3.5mm light pipe in the parts list. Since that prototypes assembly I have experimented with different LEDs and larger diameter(6mm) light pipe. The parts list only shows the newer LEDs of choice, but includes both versions of the light pipe since that is to some extent a design choice.
The 6mm diameter light pipe is far more visible and brighter than the 3.5mm, however it is stiffer and somewhat harder to work with. Any future jacket prototypes I make will be using the 6mm diameter light pipe.
The current prototype version I have made using the 3.5mm light pipe and dimmer LEDs is fairly difficult to see the actual signals during daylight, however at night it is quite apparent. Switching to the larger 6mm light pipe and doubling the MCD of the LEDs hopefully should help aide in that issue some, but I have not upgraded the prototype jacket for outdoor tests yet.