The main potential drawback is whether it is compatible with the standard igniter and ecu setup. There are a number of things you will need to know - Will it work CORRECTLY, WITHIN SPEC. with the dwell time used by the standard ECU ? Will it draw excessive current from the igniter thus overloading it ? Will it generate excessive voltage on the primary at spark and overload the igniter ? (40KV and 70:1 means nearly 600V, seems very high to me).
I would also want to know how the output compares to standard as you may find no benefit whatsoever.
It's quite likely it would appear to work if you wire it in, but failure may be just around the corner for any of the reasons above - including engine failure as a result of over-advanced ignition.
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