Just for the record.
There are two HV coils, one is on the PCB - this one produced about 400 a 600 Volt and don't need any tape.
The other one (bobine) between the PCB and the spark produced about 20.000 Volt and NEED tape between all layers AND the low Voltage (400 - 600 Volt) site who is coming from the PCB.
This is the homemade bobine
http://home.online.no/~jon-mj/homemade_coil.htm
And this is a homemade HV-coil
http://home.online.no/~jon-mj/images/cdi_ig4.jpg