unless you were getting spark blow out you will not see any difference in dyno numbers
That is not a completely true statement. "Lighting the fire" is more than a simple it did / it did not type of thing. "Spark blowout" (aka: no spark due to inability of the coil to generate sufficient voltage to ionize the spark gap) is only he WORSE case scenario of insufficient ignition.
Basically, an electrical spark is a REALLY crappy way to light off an air/fuel mixture! Why do you think IC engines are SO picky about A/F? An open flame can light mixtures that are MUCH richer or leaner than an electrical spark can. But, it is MUCH easier to generate an electrical spark at the right time inside a combustion chamber, so that is what we have.
The more power you can dump into that spark, the "hotter" the spark is and the better the initial ignition event is. A coil that JUST has enough energy to generate the ionization voltage will NOT have much energy left to generate current in the spark gap. Power = Voltage * Current, so you really need BOTH voltage and current to create a strong, powerful spark.
So how do we get a "hotter" spark? Well, we need to get MORE energy into the coil on the primary side so the energy will be there to generate the voltage and current on the secondary side. Boost-A-Spark claims to do just that by RAISING the voltage on the primary side of the coil. Power is also equal to Voltage squared divided by the resistance of the circuit (coil). So, raising the voltage SQUARES the power going into coil. For example, raising the voltage by 10% will raise the power stored in the coil by 21%. If you could double the voltage to the coil then you would have FOUR times the power stored in the coil.
Once you have more power in the coil, you can play games with the spark gap to increase the voltage of the spark event itself. This larger gap helps create that "hotter" spark AND it exposes MORE of the A/F mixture to the initial spark, so it gets the ball rolling quicker. Again, all good things.
So, a better spark CAN increase power even if you DIDN'T have spark blow out simply by getting the ignition even going faster and cleaner initially. Remember, ignition advance is an attempt to get around the fact that the ignition and combustion event does NOT take place instantly.
In a perfect world, we would want ALL of the mixture to burn instantly at TDC so it would have the maximum combustion pressure pushing the piston down the bore as long as possible. We play with advance to get that peak pressure to occur shortly after TCD. The faster we can light the fire, the shorter the combustion event, the closer we can get to the optimum situation.
& HTH
