I always thot them to be snake oil, but the e 3 plugs got better gas mileage than anything else . That being said , the arc is going to go to the closest ground on any of them.
I`m running ngk`s too-------------
Hard to beat GM's HEI and .050 gaped NGK's.
Funny how no one gives me grief over my passenger side inner fender mounted Nissan windshield washer tank, but flips out about the GM HEI.:D