I Decided to build my own circuit and test GM Twin Post Coil Packs and share the results as there was no testing or results around on the internet, also to debunk coil myths with MSD and L67 Coil packs having more voltage potential.

My circuit was built using a IRF740 N Mosfet a diode and 2 resistors, driven by a Frequency Generator and bench power supply. The LSX Coils were used with another box to drive them. Links included below for the coils purchased new.

GORST Coil
https://www.aliexpress.com/item/Car-Automobile-Ignition-Coil-for-BUICK-CADILLAC-CHEVROLET-ISUZU-LOTUS-OLDSMOBILE-OPEL-PONTIAC-VAUXHALL-OE-No/32759165758.html

CAD Coil
http://www.ebay.com.au/itm/122278526703?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Spark Gap Tester Device
http://www.ebay.com.au/itm/272478410025?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Wikipedia link for free air voltage vs spark jump distance
https://en.wikipedia.org/wiki/Spark_gap

Discussion thread here to
https://pcmhacking.net/forums/viewtopic.php?f=31&t=5136

The Results below are Maximum Gap in millimeters that the coil could bridge with an ARC, measured at 3ms Dwell Time and 14volts.
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Here are a OEM GM and MSD coils insides after cutting the coil in half.
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NOTE: Genuine Delphi Coils have Markings on them.
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