Getting Retarded
As previously mentioned the JNMM will retard your ignition timing when you spray, but it costs over $200. There are cheaper options.
Crane and MSD both make a timing controller adjustable up to 20 degrees of retard. I couldn't find a simple diagram of the MSD unit, but I'm assuming that it is the same as the Crane unit, which we do have a diagram for.
The Crane unit is activated by grounding the yellow wire from the unit. To just run retard during the second stage splice the yellow wire into the green wire before the pushbutton switch. The Crane unit goes for $140 on Summit.
Another way to retard timing is to use MSD's digital 6 ignition. It is part number MSD-6520 and goes for $280. The MSD 6A(MSD-6200) coupled with the Crane timing controller would cost $290. The downside of the MSD digital ignition is that it only has 10 degrees of timing retard available, but you will have to be running a very large shot for this to become a limiting factor. The ignition control is activated by a 12V power source being attached to the pink wire coming out of the MSD ignition.
