Here is a few Q&A's that might help you understand the nature of the Kozmic oil catch can for the Mazdaspeed.
Q: Why Do I need a Catch Can? What does it Really Do?
A: All motors suffer from "piston blow-by" during a combustion event in the cylinder. Forced Induction (turbo, supercharger,etc) see a very tremendous amount of blow by due to the fact you are creating a positive charge entering the cylinder and in turn making a bigger "boom". While Naturally Aspirated motors can see gains from a proper ventilation system, forced inductions cars will see an extreme gain comparatively.
Q: What am I actually gaining from venting the crankcase with the catch can?
A: Positive pressure in the crankcase creates pressure on your pistons as they are coming down, you will notice in the charts below that spool and low end (even in a stock turbo situation) was improved. The main reason for purchasing this kit is not HP gains, that is the bonus. What you can expect from this kit and venting the engine properly is better oil longevity, your oil will not break down as fast, as the catch can is catching alot of the contaminates and gasses that break down your oil (leading to longer bearing/motor life). Another positive side to venting the crankcase, especially on the Mazdaspeed3 is that your seals/gaskets will hold up longer oil pan, rear main seals, crank seals, timing cover sealant, most of these do not go out from age, but from constant changing in pressure and moving so slightly as to change how they ride on the cams/crank - causing them to leak in most cases after time.
Q: Why is no one else running a kit setup like this?
A: "We are not out to re-invent the wheel, we just want it to turn faster" . Look at what other communities are doing in the automotive world for catch can systems, and you will find that many run a setup very similar. This is a proven part if manufactured and designed correctly.