Doesn't sound viable to me either.
If you want cleaner emissions, there's always a catalytic converter. Not to sound like a smart-ars or anything...but that is a proven technology.
I can understand wanting to run a cat, if you don't like the exhaust fumes wafting in through open windows in the summer. You can always run a cat, even if you aren't required to. The modern high flow cats don't significantly affect horsepower anymore. And go for about $65 at Summit.
But watch out for these "snake oil" solutions.
A capacitor would steal some of the spark energy to charge itself up, and that would definitely reduce the voltage across the spark gap, resulting in even more incomplete combustion.
Why not consider a multiple spark ignition system? There are several out there, and they definitely work. Hotter spark and multiple spark, will result in better combustion and greater efficiency.
