Original poster: "Black Moon" <black_moons-at-hotmail-dot-com> Opps, sorry about that, forgot some info, the secondary pipe is 1 and 1/4" but the secondary itself is 1 and 3/4 inch or so, and the spark gap is set at 2mm or about just over 1/16th of an inch (Power supply is a flyback, so can't go much higher atm)