Here's a summary of the S&S IST (Intelligent spark technology) Ignition by S&S... http://www.sscycle.com/

S&S IST Ignition Modules and Installation Kits
This new Intelligent Spark Technology ignition is as advanced as any on the market, and generations ahead of most. Its most distinctive feature is Active Detonation Control, which relies upon input from various sensors to optimize spark timing and engine performance under virtually any combination of load and engine speed. This ignition determines the engine's spark-knock threshold and then retards timing just enough to prevent knock and detonation, protecting the engine while optimizing performance. It factors such as temperature or fuel octane change, the ignition automatically reprograms itself accordingly. Additional circuitry permits the IST ignition to function with reduced voltage, meaning the rider has a better chance of making it home if the charging system fails. Other benefits feature easier starting, smoother cold weather operation, and increased fuel economy.

 

Keen to try this one myself.

 

Been riding my bike with an S&S motor and IST ignition for four years now. Their motors fitted with one have a three year warranty, which is not to be sniffed at! I haven't had to use it, but it does give peace of mind.