i have this kit installed on my bike. there not that bright during the day, and don't do much good, but at night they do help a lot, and my "back off" brake flasher makes it even better..according to some of my riding buddies.
i may just add the brake light like cglennon did. but i think smaller may look better.
Good point on the brightness. I used Radiantz 1.85" LED clusters, which are super bright and very visible even in full sun light. There are lots of new LED products coming on the market these days, so you should have no problem find something comparable. I like LED for the low power consumption and impact of instant on (no buildup and decay like incandescent bulbs).
I hear you on the smaller lens. This is the one I wanted;
. It is much more compact than the one I ended up with, but it would require shaving, and possibly damaging, the LED clusters to fit.
One source for parts to consider is tractor trailer and/or RV supply stores. The one here in Portland had all kinds of LED assemblies, lenses and such. Probably not as cheap as the Internet, but you could get everything you need in one trip.
Also, as KM pointed out, this is a two wire installation brake light only, no running light. For those electrically-challenged, I recommend Posi-Lock and Posi-Tap connections; fast, easy, strong and semi-permanent. Best connectors I've found on the market.
A second brake light is an easy and relatively cheap mod that increases your visibility. It's been proven to work with autos and I can attest it works for motorcycles. Highly recommend.