No matter who's ignition box you buy, most can do multi-spark to 3500 rpm max.
I've O-scoped the stock coil system and then we swapped out 3 other boxes and coils
and none of them gave a substantial change(power wise), but all the multi sparc systems
idled better and had better cruising manners. (MSD, Crane, Jacobs) At crawling speeds
they seem to help response.
Too much spark can be a bad thing, it can arc to the piston top if you go too crazy...
Bad things happen if this occurrs...
Dave