Hi,

I have seen a type of braided spark plug inner wire, but only on expensive "hot rod" wires for cars, boats, etc. In any case, yes you can shorten the wire. Just cut it to length, then strip back the insulation carefully, and you will expose the inner wire, of whatever type it may be. It depends on what type of spark plug connector you have, but I usually fold a small 1/4" or so section of the inner wire back along the outer insulation, then reinstall the spark plug connector. If the plug wire has an outer braiding, or shield, you can just cut this back as well, or do as Mike suggests. Make sure this outer braid, if you have it, does not make contact with, nor come close to the spark plug connector or inner wire.

Good luck,
AV8TOR