For years the plug for the 2L was/is the NGK BP6ES. 6 indicates the heat
range, 5 is hotter, 7 colder. E indicates an extended electrode and S if I
remember right is a standard copper core. I've used Bosch platinum's in my
BMW but not in the Roadster. The nice thing about the platinum's is that
they last a long time (60K+ miles). The multi tip plug thing has been
around for a while. Mazda rotary's use them but I think that has more to do
with the way the plug fits into the rotary "Combustion Chamber". As far as
I know, when the plug fires it's only going to arc once to one place. I
think an MSD ignition would provide more of a difference than splitfire like
plugs.
FWIW
Brian
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