Demand and Supply
All I'm saying is that the other 2 have more performance parts available than the mopars
the other 2 sold more cars than mopar :)
And Mopar engines were already performance, they just strangled them for granny use with a 2bbl
for example you won't find a mopar head, from the muscle car era, where the inlet and exhaust valves are not centred to open into the widest part of the bore, centre of valve head is always on the diameter line of the cylinder bore. this reduces the impact of shrouding by the cylinder wall on the flow past the valve
you will find the oposition offset their valves to the top or bottom of the cylinder to either accomodate pushrods, bolts or rocker gear, and valves do not open into the widest part of the bore, increasing the shrouding caused by the cylinder wall
so to counter that handicap you'd need some performance equipment from the aftermarket.
Performance cams, higher ratio rockers and heavier springs or a different better cylinder head
silly opposition
Dave