Ok what is the difference between a BOV and wastegate? As I understand it the wastegate controls the level of boost, while the BOV releases large amounts of pressure during gear changes and the like
Hey BiX , from what I understand:
The wastegate is a valve that is on the actual turbo unit. It is like a switch. Ok, so this switch is on the intake side, the switch is basically a
spring connected to an acutator rod. When the pressure on the intake side gets to a certain point (eg. 14PSI or however hard the spring is etc) the
switch pushes the acutator rod which opens a valve on the exhaust side of the turbo, this lets exhaust gas bypass the turbine on the turbo, so it wont
make any more boost.
A blow off valve, is much simpler, if you imagine a car on boost, the turbo is shovelling lots of air into the engine. When you suddenly lift off the
accelerator the throttle body shuts closed, the air the turbo is pushing cant go in the engine because of this. The only way the air has to go is back
where it came from, which is through the turbo. Thats where you get that choppy air noise from when u hear a turbo change gears sometimes. Because
the air is going backwards through the turbo it slows it down, so when you get to the next gear, it'll take that extra bit longer to spin the turbo
up again.
This is where a BOV comes in. it is like a pressure relief valve, when the throttle body is closed, and the air has nowhere to go, the BOV opens at
a set pressure and vents the air to atmosphere, thats why you get the pshhht sound. Its better to plumb it back to the beginning of the intake
because you can upset the fuel/air mixture. You lose the pssht sound though 
Factory turbo cars are always plumbed back
[Edited on 9-6-2004 by Che Castro]
But if you lose the PSSHT sound wheres the w##k value 
It goes with the coffee can exhaust, its more important to look and sound fast than actually be fast.
but then if u dont have the PSSSHHT the no one will look at u when u change gears down george st! Get your priorities straight :P
You can now buy PA 'Pssst' systems.
You press a button and the 'Pssst' sound emerges from a speaker.
You can even connect it to a vacuum switch so it automatically will sound when you change gears.
trust me I don't want one, just a question from and engineering view point
Fake BOV 
http://www.takakaira.com/accessories/nightpager/nightpager.html
Dam gots ta get me one of those,so i can go wrex huntin :vader