It doesnt affect which stage you have or not. before i purchased my BOV, my friend has his on his stock '03, and it sounds the same as what i have with my S2...

 

What makes the sound inbetween shifts that sounds like nitrous(which i know it isnt). Is it the wastegate acuator or the blow off valve?
Im kind of a newb in car modding

 

Okay DR, turbo school is now in session.



Okay, the above shows the basic system. The blue section is pressurized under boost. Now when you get off the throttle, the exhuast stops pushing the turbine blades. So the turbine wheel slows, along with the compressor wheel. Now, without some way to relieve that pressure, the pressuized air (blue) hits the compressor section like a shockwave, causing wear and tear to the the compressor wheel and the bearings.

So, what happens is that when you get off the gas, there is the BOV (to be technically accurate, it's a diverter valve, stock mode is an internally vented diverter valve, aftermarket or Mopar plate are externally vented diverter valves) which send that pressure elsewhere.
That is the noise you here. Psshh

The above illusrtation courtesy of howstuffworks.com Great place.

http://auto.howstuffworks.com/turbo.htm

 

So its not the wastegate acuator or the blow off valve that make the sound?

 

I've been a fan of HSW for awhile, I agree, great place!!!!

 

Well, kinda See, BOV and diverter valve (confusingly enough, also referred to by some PVO guys as an anti-surge valve) are the differnt names for the same item. Not the wastegate, it does not make the noise. Just the BOV.