Yes the .003 is mimimal. If it sat in the button further, it would change the affects of using a turbo button in he first place, as with standard buttons, the glowplugs sits uneven to the top of dome, and you cannot shape the top of combustion chamber as tight with a standard glowplugs as you could with a Turbo. That why the turbo head button and glowplugs are supposed to produce more power, they run a tighter closer combustion chamber due to the small taper on the end of the plug.