You guys are missing the point a bit.

Turbos have an effective range where they move the most amount of air with the smallest heat generation. The translation to how many PSI that is depends on the size of the engine.

Now, how does this help to make power? It's a combination of putting more oxygen in the cylinder, keeping the intake charge cool [so that you can go back to the first item of having more oxygen in the cylinder] , and most importantly, raising the peak cylinder pressures during compression.

So far, I haven't mentioned compression ratio at all [current case exlcuded], and that's because for the most part, the info so far on this thread is accurate. So why, then, do most people view a lower compression engine better for boost?

The answer is actually pretty simple. You can only increase the cylinder pressures during compression so much before gasoline spontaneously ignites [detonation, pinging, whatever you want to call it, it's bad]. What happens, then, is that when you boost a high compression engine, the boost makes a larger effect on the peak cylinder pressures than the same boost level on a similar engine with a lower compression ratio. So why, again, do most people view a lower compression engine better for boost?

With a lower compression ratio to deal with, you can inch yourself closer to the maximum cylinder pressure for the given fuel you're using easier than you can with the relatively constrictive range of boost you can deal with on a high compression engine. The downside, again, is that you need a turbo that will operate efficiently to provide the necessary amount of air according to the three guidelines I covered earlier.

Another thing to keep in mind is that anytime you compress air, it gets heated, and since you make your power from the rapid expansion of air in the cylinder, the lower the beginning temperature theorhetically yeilds the greatest change in temperature in the cylinder, which means the fastest/most forceful expansion, which equals power. I take this to mean that if you can compress more air more efficiently and then compress it in the cylinder with the least amount of extra heat generated, the more power you will make. So far, most turbo engine manufacturers/racers agree with this.

In this forum, pretty much anyone that mentions CFM talking about a turbo is likely to be someone that I've told/taught about boost. CFM [cubic feet per minute] is a measure of how much air the compressor will flow efficiently [ie- low temperature increase], and so that is the context it is mentioned, not as a literal definition of how much air the engine will ingest in a cycle, only how much air it can move effectively enough to be useful.