OK, just shortened the HT Lead which was on the car when I bought it about a year ago and so am not sure what length the OEM part is. Suffice to say I was eventually able to shorten it by almost two thirds of it's original length.
Once again I haven't tested the output voltage from the end the shortened HT lead compared to the original length but it will be a bit stronger simply due to the reduced resistance which cannot do any harm. Not difficult to complete, works fine and should improve things...