I have not done any tests but I believe if One Mag and One Electronic Ignition is used you are likely to fail the Mag Coil prematurely (that would reduce the aprox. 400 to 600 hour normal failure of a new Slick to a really unacceptable life).  Why??  One of the principal advantages of EI is the variable timing advance that improves power and efficiency.  When the EI fires a plug before the Mag, the pressure rise from earlier combustion may prevent the Mag plug from firing.  Maybe (probably?) preventing the Mag plug from firing at least at higher altitudes where advance is the greatest. I base my theory on the old Champion Spark Plug Testers that used an air hose to increase pressure while firing a plug to check its ability to continue to fire.  What do others say?  Steve Colwell

Steve, I don't think the pressure rise should cause a mag problem.  Remember both fire before TDC.  Actually I once wondered if the staggered fire of dual ignition would improve burn quality.  However, General Motors shut down an engine program before I could obtain 1st hand data.  I have a patent for a dual ignition engine design but the engine never ran.  I would like to see some dyno data.....interesting subject.

Craig Berland