Maybe somebody made a research which COP (coils-on-plug) can be use in our cbr400 engine? I don't really care for now about dwell time, resistance/inductance and so on, because my EMS module able to setup for any of these parameters. The main point for me is size - I have tried Kawasaki ZX6R COPs and it looks like ok, but I like little bit smaller length.
Here is kawasaki.

Maybe something like this size:

For those who're interesting to use COP with your stock ignition system, you can use Bosch 0 227 100 124 which allow you to get very good spark in wasted spark mode at your cbr400. Here is link: http://www.microsquirt.info/Bosch_211.htm