Jagwire cables are poor quality. Don't get taken in by fancy concepts such as PTFE coatings and other rubbish. That stuff comes off and creates friction, not prevent it.
It is very difficult for the layman to judge the quality of cables because the differences are literally microscopic. Regular cable is made up for multiple strands of steel wire. Good cable undergoes one more process - the cable is drawn through a die afterwards to flatten the outer ridges. Imagine a cut-through section of a cable, it will look like a daisy with round petals. Once it has been pulled through a die, the petals will have flattened outer edges to create a smoother circumference. This process is expensive, but worth it.
Guarantee that you get that by buying either Shimano or Campag cable. Nothing else comes close. Buy a length and cut as you need. I don't see the point of pre-cut sections since you'll be trimming it in anyway.
Finally, cut using a cable cutter, not a side cutter.
