Forget the 25v capacitor, go for one with a higher voltage rating, say 64 or 100.
I was thinking of that... But how about getting a jolt out of say 64V? as of the moment, I've tested the possible caps by hooking them onto the 9v battery in the reverse fashion and they seem to heat after some time but no flames so far. Will still consider the above option if someone can confirm. Lol! its been crazy with me setting up all combinations of caps plugged in and waiting to see if they may explode!