Steve, I know the circuit, it is how I build mine too.
Andreas, didn't know about the high impedance of the goldcaps. Just thought goldcaps have the highest capacity at the lowest physical volume. Speaking about goldcaps, I thought about using them for another application too. I wanted to use the spark to perforate thin alufoil to make pinholes. Do you think I am better of with normal electrolytics for this application too?