Might try cutting off the whole horizontle leg of the ground strap till your into the angled portion on the side which'll totally unshroud/expose the spark kernel to the chamber. Leave just enough angle/length so you can bend it slightly to restore the gap as it wears. Dont know if it made a significant difference but it made me feel better thinking I had done something "trick" . Keeping the edges filed sharp does reduce the required voltage to jump the gap