Unfortunately CFM ratings don't really mean much. You can push as much air through a pipe as you want as long as there is enough pressure.
There are standardized tests, but many companies will fudge the results to make their product look better.
In an exhaust the only restriction is the muffler. And the cat if you count that.
The intake is only the filter really.
There is some simple math you can do to figure out how much air is going through your engine at any time. We know the size of the engine, so we can calculate the amount of air that goes through at any RPM.
in a four stroke engine, air is pulled in or pushed out every other revolution. Which means for every RPM there is one liter of air pulled in. Or 1.2 for the SX.
So at 2000 RPM there is 2000 liters of air going in every minute. And from there it's a simple conversion to get the CFM.
To get the flow for the exhaust you have to use some more math to find out how much extra volume the burnt gas has added to the charge in the cylinder. That will tell you how much is flowing through the exhaust.
Keep in mind all of this is in an idealized system, actuall values will likely be lower.
I hope this helps.