Generic blowoff valve? and some other Q's
 

Is there any such thing as a generic blowoff valve? No expensive shit like Greddy or HKS but just something that relieves pressure? I thoguht zbrown might have used something like this in his N/A Supercharging project since his bypass valve and BoV were so damn cheap..
And another thing. How do you determine when there is "excess" pressure that needs to be relieved, do you have to set something, or does it just "Take care of itself" based on the engine? im sorry for the extremely stupid questions, but I'm an NA owner trying to educate myself.

It's not even so much the "excess pressure" that's the problem. It's the fact that when you are driving and allll that air is moving in one direction and you snap the throttle plates closed (shifting for example) all that air wants to stop and go back where it came from, so then the BOV has to let it out. It's more "Turbo back-pressure release valve" than "Blow off" anyway. The way it's determined is how tight you have the spring in the BOV itself, which honestly, you don't really need to adjust, it just knows, ooOooOooooh.

excellent, thanks for the responses.