I decided to modify my engine's distributor to accommodate a dual ignition system.   A few years ago, Paul Messinger wrote an instruction manual for converting a distributor for dual ignition.  This manual entitled "The Dual Pickup Modification for the Subaru EA-81 ND Distributor and Related HI distributor - Instruction Manual" is freely available from Paul (paulm@olypen.com").  He also makes a kit for the conversion.  Although I could have purchased a second pickup coil to put in my distributor, I did not need that as I had two Nippodenso distributors on hand (and one Hitachi).  I got that second ND distributor on eBay a while ago for something like $10US. 

When I first installed this combination (June or July 2003), I found it was difficult to start the engine.  The engine starter was not turning fast enough to get the ignition module to detect the pulses from the pickups.... I thought it was because of my flywheel/starter combination.  Later, in  April 2004, I found someone using the ND/GM system with the same engine as I have... so I decided to try again and it worked!   I figure my 2003 attempts failed because of too long battery leads (10 feet of 4AWG booster cables and 15 feet of cables in the aircraft (from the back of the plane)).

Assembly and testing of the Nippodenso dual dizzy

As I was getting difficulties with the ND/GM setup, I consulted the Airsoob discussion forum  and a few people suggested I try to make a different conversion using Mitsubishi integrated pickups/control modules.  I discussed this with Paul and I sent him a Hyundai dizzy for testing on his distributor machine.  Paul then made a conversion kit that I used to convert a Subaru Hitachi distributor using two Mitsubishi control modules.  I ended up not using the system since I got the ND/GM HEI to work.

Assembly of the Hitachi/Mitsubishi dual dizzy