E-3 plugs worth the money?

TrailBeast said

Waste of money.
NGK is my preferred brand as well since they run right ALWAYS.
I'm the HEI guy mentioned above by the way. :D

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I put a set in my Daughters Jeep 3.7.
I did see a noticeable power difference & fuel mileage gain of a 1/2 MPG.
Haven't used them in anything else.