By my read of their report, there wasn't an exact apples-to-apples comparison. The cases where the report shows dual mags giving more horsepower/speed are ones where they left the timing of the EI fixed (at 41, 36, and 30 degrees) while the mags naturally stayed at 25 degrees throughout. Seems like the mags' "advantage" in this case was having more optimum timing for those rich conditions vs. the timing the EI was fixed at.
I think more interesting would be comparisons of mags vs. dual EI fixed at 25, and mags vs. dual EI with a fully-optimized timing curve. I'd expect the EI would show a clear advantage in cases outside those where 25 degrees is about the optimum timing point.