If you are using the stock ECU you will need to keep the stock igniters.

Does it matter that the stock coil packs have only got one ground for all three coils?

That is not correct. The ground is what triggers the coil, each coil pack is going to have three grounds and one positive. If it were what you are saying then all three coils would fire at once, which they do not.

That makes more sense then, becuase the coil packs have four wires, three yellow and one thick, black one. Just by looking at it you would expect black to be the negative, not the positive... so lucky I asked!

Thanks for the help. :)

Thanks Banzai, good info

I installed the unit today without any issues, however I do not have the Tacho any more. It works for a bit but is very very jumpy and after a few moments of driving, it seems to stop working all togethet.

I read another thread elsehwere talking about the same issue, and the person who replied mentioned something about the DLI not working because of the wasted spark setup.

I was wondering if it is fine to run the car this way? I data logged the emanage ultimate and it looked like it was getting an accurate RPM signal, but I can be so sure about the factory ECU that is being piggybacked.

Which Twin Power did you install? The one specifically for rotaries (2nd and 3rd gen Rx-7)?

I installed the DLI. I realise that their is a rotary specific version, but the fact that they dont cater for the 20B is an issue.

Is it true you can NOT use platinum (or iridium) spark plugs with these Twin power units?

HKS recommends right on their website that the Twin Power only be used with resistor-type plugs. I know people are using the non-resistor plugs anyway, but that is what HKS recommends. Resistor plugs have an "R" in them if they use NGK nomenclature, like BUR9EQ.