Looking at dyno sheets of before and after for the boss intake manifold I wouldn't expect much of a drop in e/t.
Peak numbers don't mean anything, all that matters is area under the curve and the boss manifold loses power in the mid range and then gains right near red line. I'd expect the area under the curve to be only slightly changed.
There is a reason that Ford didn't just put a different manifold on the Boss and call it a day.