i'm using the harley taillight module that makes the turn signals also glow as running lights and still work as turn signals. the kit includes the red lenses. the next thing i did to improve visibility was installing the B.A.L. and it stands for bright *** light. it sure is bright indeed. i keep it set on the brightest tail light setting and the brightest flashing brake light. all this was done to hopefully keep some 22 year old kid from rear ending me while they're texting. the BAL is so bright that you can't ignore it at all.

 

The change in brightness is minimal at best. My opinion, it's only for looks and with the LEDs behind the grey lens it was a step backwards. The LEDs are mounted on a white circuit board which shows through the grey lens. I used a marker to black out the circuit board - looks better now.

I added the run/brake/turn module and bullet lights to my RKC (And now the Ultra.). With the red bullet lens the signal lights weren't very obvious, according to the guys I ride with. I installed LED lights in the signals which greatly improved the visibility of the lights but then the brake light wasn't as obvious. I installed the LED brake light to complete the package (Both bikes.). Now the guys I ride with want me to be the last rider in the group - my lights are too bright and it hurts their eyes to follow, especially when it gets darker out. Perfect!