Can better ignition add HP?

ok well I've got magnecore wires and denso plugs, and I know those can add a few HP...but what about a MSD coil and ignition? Can that add an HP? What would be the advantage of having these and how much would it cost?

Thanks,
Chance

Also how much HP would an ECU add, and what are the disadvantages of having a Jim wolf ECU?  Better gas milage? Worse? The same?  Can it lessen engine life?

Thanks,
Chance