Your opinion on equal length spark plug wires?

ir3333 said
...so are expensive 8 or 8.5 mm wires necessary or are standard auto parts store 7 mm adequate as long as they are in good shape with no leaks?

That's a different question.

Insulation helps to keep the energy contained.

To put the answer of time difference in traveling an extra foot assuming 186,000miles/sec

.000000001 seconds.

If someone can tune an engine to factor in the travel timechange on a set of plug wires, they are building the wrong stuff!

Zero gain/loss and a waste of time and effort exercises.