Don't waste your time modifying a Gen 6 like this.
The injector drivers inside a Gen 6 are quite capable of running high or low impedance injectors. The problem with the Gen 6 is that the unit doesn't capably dissipate the heat that is generated under continuous high duty cycle operation. When I worked at DFI I tested lots of Gen 6 units that were returned for service. The test fixture there uses a wet-flow bench with a set of low-impedance injectors. If I set the unit to run at anything over about 40% duty cycle, within a minute or two it would be too hot to touch. Obviously this could lead to problems after a while.
The Gen 6 uses the exact same injector drivers that the older FAST units used for years. The primary differences with respect to this issue are that the FAST unit used 8 drivers instead of 4, and the enclosure was much more capable of dissipating heat. I didn't need to replace too many injector drivers at DFI, but in 4 1/2 years at FAST, I never had to replace a single one.
Don't get too worked up about 1 injector per driver vs. 2 injectors per driver. It makes no difference to the driver in terms of power dissipation. The driver regulates output current to 1 amp, regardless of whether you have 1 injector connected or 50. Of course only having four drivers prevents the possibility of running sequential injection on anything over 4 cylinders, but the Gen 6 is a batch-fire unit by design anyway so that is a moot point.
All in all I would say don't sink money into a Gen 6 trying to make it something it will never be. Newer systems offer much more than the Gen 6, and if you are intent on spending money for better performance, replacing the Gen 6 entirely is the only solution in my opinion. I don't love every single thing about the Gen 7, but I really like the new version of CalMap.
