I want a brighter brake light

The first thing you can do is go to the Bulb Comparison Chart and find which one will work best for you.

Elsewhere in the FAQ you will find a writeup on adding bulbs into the empty pods next to your brake light. This adds significantly to your safety out on the road.

One product you can buy is from Aerostich, the Stopper LED Brake Light. This is a row of LED lights that attaches to the top or bottom of your license plate. It acts like the middle brake light on a cage and will give you more visibility.

You can put Hyper-Lites (LED modules with flasher) in the extra pods. You can see the installation and a demonstration here. They're very effective, plus they give you extra running and brake lights if your incandescent center bulb goes bye-bye. $80 or so shipped. Get the generic dual-function model (for running and brake lights) from this page. They may not be as easy to install as the Kisan, but they're cheaper and provide a number of additional benefits.

For installation in the two spare pods, it's recommended to undo the two bolts holding the rear taillight on the bike, and install the Hyper-Lites with the light assembly off the bike. It's a very clean installation; you can hardly tell it's there until the extra lights come on.