Here is more, I installed dual plug last winter. This turned out real good with a spark timing reduction of some 8 dgr as a general number. The Hemi has as we all know a big combustion chamber thatt require a large piston dome, creating an egg shell shape chamber. Dual plug will shorten the flame travel on this motor and a shorter timing will create less piston force on the piston uppway travel and a more pecise cylinder pressure on the right dgr. I should raise the cr ratio to some 14:1 for E85 to see what the fuel consuption will be. Today it is 15 mpg E85 which equlize 21 mpg on gas, on steady state 60 mph.

I use steel valve cowers, these are lighter than the cast aluminium stuff.

The COP coils are nearly like Hemi stock stuff.
Goran
I am a 69 years old sportscar freak living in Sweden with a Hemi equipped Pantera.