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Has anyone tried this?
If you don't know what this is, it's adding shims to the spark plugs so that the position of the ground strap is controlled.

Looking at the plug location in the cylinder head, I would guess that having the open side pointed downward would provide a better flame expansion path, vs point down or to the side.
Maybe point the open side down and towards the intake (45 degrees)?
Maybe towards the intake valves?
The theory two fold:
1. The ground strap impedes the growth of the flame, so you want to put that towards the shortest path in the cylinder.
2. The ground strap impedes the air/fuel from reaching the plug, so you put it away from the intake valves.

I can get a 50 pack of 0.01" shims for $23.
Each shim rotates the plug between 52 and 61 degrees (uncertainty is because I don't recall if the plugs are fine or course thread).

Looking online, consensus is anywhere from 0-4% HP and 0-2% MPG gains.
No one says it that it makes things worse. Many say that it makes no improvements.
But I'm an engineer :nerd: so if I can get 0.5% each from 20 different mods, I'm suddenly up 10% HP!
(One can dream, right? :doh:)
 

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Very miniscule gain, nothing you'll feel.

I'd save it for last, after nitrous, blower, turbo, and intercooler, along with every go-fast mod in the Jegs catalog. 馃檪

It's one of the last efforts to shave 1/1000 off your ET.
 

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1 or 2 hp? That's essentially a difference in humidity.
 
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