ran a twin plug setup on my matchy road race motor,it's all to do with flame propagation,with old school high domed style pistons the combustion flame has to travel from the side where the plug is to the other side,this does take significant time,(traditionally overcome by big advanced ignition timing),where theres opposing twin firing plugs ,there is a more complete/instant flame burn,(shorter flame path),but the greater gain i could appreciate is in the ignition timing which can be significantly retarded,thereby giving the bigend a easier life expectancy,in my own motor it was from 38 to 28deg,addmitedly my comp ratio wasn't extreme,only 10.75 to 1,but the motor was a more forgiving beast for it,unusual to be twin plugging a SR type head,as their pistons generally are a flatish dome on top??,maybe just the bling factor??
,,or indeed saving the bigend from high comp effects?,
