Now that's interesting information thank you Chris W.
The thing is, I never set out to purposely buy carbon core lead, but I just found the colour appealing, and in the end it was only £1.90 for a meter delivered, so it's not like I paid much.
I did actually measure the resistence of the lead when I cut the ends off to get fresh core material when I was measuring the continuity of it in one of my previous posts. The resistence was only about 2.7k ohms. Now that might seem like a lot, and ideally it isn't required unless perhaps one does not want to use a 5k resistored cap, but even with the internal resistence of the HT lead included that I don't think would have an effect on running, so long as continuity was maintained (my issue in the first instance).
I've actually had a past problem with a HT cap on my Honda CX500 that was giving a resistence of 65k ohms, and other than a much harder/longer starting, and a slightly lumpy idle, it ran fairly well considering..
Perhaps the VAPE is different though in it's requirements and like I say, very interesting point Chris.