out of curiosity... did "safety switch" refer to a boost controller? maybe a wastegate?

 

Any time there is going to be positive pressure involved, there should be some way to vent the postive crank case pressure in the works. ANY positive pressure applied to the bottom of the rings is going to net you some type of problem. It's just a ticking time bomb man.. read up on it a little bit.. u'll see how important it really is.

 

It doesn't catch blow off gases, it catches oil and gasoline vapors created in the crankcase. The Greddy can would only be suitable for an N/A application since it isn't an open breather can, so the gases have no where to go when the PCV is shut under boost pressure. You would have to add an open breather to it in order to use it effectively on a forced induction setup.

You can buy one, but it won't do much of anything until you are running a more aggressive engine setup. Personally, money is better spent elsewhere.