So, I'm new to tuning rotary engines, I haven't played with ms2 and tuner studio in years. Well I had a buddy buy a ms2 kit for his miata but turned around and ended up getting a pnp unit so he gave me the ms2 kit i put it together. I ordered a ms3 board and expansion board. I was doing some research and came across split ignition timing for the trailing coils but I'm a little confused of the relevance from what I've seen it has very little effect advancing timing but you definitely want a split to keep from detonation or is that more of just a very conservative train of thought that some people have.

 

Simplified, the trailing coils fire slightly after the leading coils because the trailing plugs are higher in the housing than the leading, and firing them at the same times in certain conditions (ie. boost) would be like advancing timing. How much depends on the year of the housings as Mazda played a bit with plug positions over the years.

Trailing plugs are mainly for a complete burn as the combustion chamber is long and there is always some fuel trapped at the trailing apex seal. In general trailing split doesn't have a big effect on power but more on fuel economy and emissions.

For example, in the RX-8 Mazda runs negative split, firing trailings before leadings, at light load to start the burn nearer the trailing edge for more complete combustion.