High Output Coil

Just because it says 45Kv does not mean it will put that out all the time. Coils are kindof self adjusting. If circumstances in the chamber are such that it only requires 20Kv, then that is what the coil will put out. If it requires 30Kv in a different circumstance, then it will put out 30Kv. And so on.The coil only puts out what it needs to, to initiate the spark and push it across the gap,under whatever the chamber conditions are.
Some things the require only modest output are; small plug-gaps,specialty plugs,and maybe cruising. Some things that require a little more output are;lean-runing,modest acceleration,and higher compression.And full-load,full power acceleration wants the maximum.
But to quote Smokey Yunich; "I think 20,000 volts is actually enough--but what an ignition really needs is a long spark duration--and high amperage."
Enter Capacitor Discharge Ignition.And multi-spark.
But for most of us with modest output engines, and reasonably close AFRs,the typical HO stuff works.