I don't have first hand experience with this particular upgrade.
However combine more fire power with a low resistance plug like a Denso IT-20 (not sure if that the right plug for our motors) then you'll have a hotter and more dense spark. As a result you'll have more complete combustion, more power, better milage, and the ignition system will degrade slower with time.
One common mis-conception is that you can open up the plug gap with a bigger coil. That may be true.. but it does'nt mean you'll make more power. Increasing the gap also increases the resistance within the plug. That only serves to shorten the ignition system life. It also makes the plug run cooler which also hurts power. A low resistance plug is the key.... and IMO more important than the system pushing it.
A cost effective plug that I use on most of my cars is the bosch platinum +2 It has a sideways spark. Which means the spark is unshrouded and there-fore the flame front is not interupted as it propigates away from the plugs tip.
On the lightning where I'm pushing big power I run nothing but the best.. Denso IT's
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