i'm running a completey different system all together.. my ecu setup was around the $6000au mark. mercury cdi marine coils can only be used with a cdi main unit. yes the distributor is blanked off, but it has been completey gutted and is now running a custom optical sensor, i also run an optical trigger off the flywheel aswell. (all this has been setup for things to come and reliability/accuracy) no i don't use the distributor for its normal duties. that's what the autronic sm4/500r are for.
for what your doing msd coils etc are a waste. a normal bosch coil will do the job fine... the easiest way you could setup that system on your car would be to get a nismo distributor and adaptor plate, or modify your stock distributor to accept an external coil. you cant rewire the original distributor to run the mercury coils.. A: there is only 1 ignitor on the micra.. B: there's no were near enough power to drive a cdi coil from the factory ignitor.... for a cdi coil to work properly, you need something like 600volts of electricity
.. having said that.. with a cdi system.. you can pump as much boost into the engine as you want with massive spark plug gaps all day every day and it won't miss a beat
were as with a stock ignition i'd say any more then 20ish psi would see you blowing out spark with probably a .6mm gap.. oh and by the way.. the bigger the spark plug gap you can run, the more power, etc you will make.
i guess its also worth a mention that while the ecu setup cost me a fair wack.. its also a **** load easier/tuner friendly aswell.. to give you an idea, most budget spec ecu's will require anywhere from 4-5hrs to tune from scratch.. we had the autronic tuned from first start, to full boost in 1.5hrs..
.. and it runs like a factory car.. does everything its suppose to do, start, idle, boost, cruise etc.. might i also add i still get 620km to a tank of fuel lol.. more then my blue car.. gotta be happy with that