Spark gap "gap"

I would guess that increasing spark gap gap will be more harmful to your primary
cap than your transformer.  What kills your transformer is over-voltage, i.e.:
the RF from the primary circuit getting back into the transformer at much more
than its insulation rating.  Do you have anything between the neon sec. and the
gap - RF chokes and a safety gap, for instance - to help protect from this?

Jeffrey Wiggins