Im my eyes and going back thru some of my dyno sheets and what I have learned over the years Id say they will come out equal. 10cfm gain or 1 point compression, the same power. If you have an engine that can breath better, its effective compression will increase, as it is getting more in the cylinder, more to squeeze. If you run a smaller space, more compression, you get the same effect. Ill take more compression as the engine will generally run more efficient with higher compression. Less fuel, more power.
This is why Circle Track 2bbl engines(or NASCAR restricted engines) can run 12 to 1 static compression, or MORE, on a lower octane than what you might think. They can not fill the cylinder as much, so they have to squeeze it harder to get the power. The effective compression may only be 8 to 1.
