The Boost on these cars uses and internal waste gate system that uses an actuator that operates on boost and a waste gate solenoid that the ECM uses to bleed off boost to the actuator until a certain boost is attained. The actuator opens the waste gate puck and bleeds pressure from around the exhaust wheel to the downpipe. Some will argue about a blow off valve but I personally do not beleive our cars nee them. Using the automatic trans really negates the necessity for one of these. Some will say that they help save the turbo but I do not have one and have almost 100,000 on one and numersous miles on the fast car with no problems. I do not feel they are worth the money. Spend it else where on go fast goodies. Leave the noise makers to the ricer crowd. Actually the Smaller diplacement manual shift cars are helped by this. They help to keep the turbo spooled up during gear changes.