Do good spark plug wires make a difference?
Running on bad spark plugs or spark plug wires can end up using more fuel. High-quality wires will allow the spark plugs to start faster and keep your engine running more effectively. Save money. Routinely swapping out your spark plug wires can save you cash. via
How do I choose spark plug wires?
Most manufacturers recommend an 8 or 8.5mm plug wire on most applications. Exceptions would be an all-out race car or a street rod where EMI/RFI suppression is not a concern, but weight and appearance are. In which case, a 5 or 7mm wire might be a better option. via
Where are Denso spark plugs made?
All DENSO Spark Plugs are manufactured in Japan, Indonesia, China and USA. via
How do you check a spark plug without a tester? (video)
https://www.youtube.com/watch?v=mUOmsGiirTU