Bought a "run out" special of a Bosch GT40 coil from local supermarket 'bout
a year ago. Being involved heavily with electronics I thought I,d check the
thing out against a standard coil to see what they changed. Somewhat
surprised I found the primary ( 12 volt side) and the secondary ( ouch side)
to have almost identical resistances/inductance to a standard coil!. To have
more secondary voltage you either need less turns on the primary or more on
the secondary (or both). I,ve got a suspicion the only difference here is
the colour of the "sticker".