Your call your car your money...
Ive done many repairs and replaced many dozens of spark plug cables (I had a roll of it and used to crimp connectors to the ends) - and what you are professing is completely oblivious to any rationale. By your rationale the engine suddenly had a cam profile change or caburation change, or even ignition tune up all by itself triggered by plug change.
Now if the car in test was a brand new car off the showroom floor and not attaining its claimed speed (meter down) and you corrected it by changing plugs - then you should have proceeded to smack the dealership who sold you the car.
But if the car/van was a used item and you have no conclusion that the ignition system was upto par - like rounded eroded spark plugs, incorrect dwell angle, incorrect timing etc. - then replacing original parts would have restored your "meter down"
thats what Im saying too. Such precious metal spark plugs are about long life and better facilitation of spark event.
Not to add 100 hp to your engine.
By saying something here in PW - you become either
1 fizool
2 Idiot (with experience)
3 Idiot who knows nothing
