the turbo xs does leak, it is impossible for it not too. however the leak is so slight it doesnt cause any problems. if you take it off and try to blow through the end that mounts to the car, you will here a slight hiss as air escapes. you'll have to blow hard but it does leak. however, due to the design, it is also the slowest responding unit, and under higher boost pressures you will hear it "flutter"
as for my greddy bov, it is not recirculated back to the intake, no need to. when you let off the throttle to shift, the computer cuts fuel, so this bs about running rich while shifting is just ignorant, plus even if it did, thats what, maybe 0.25-0.5 sec that its running rich? give me a break. the only real benifit to recirculating it is to help keep the turbo spooled between shifts, and again, you shift so fast when you run the engine hard it really has no effect. in order for it to run enough air through to make a difference you would have to be downshifting to slow down, and if your doing that your most likely trying to slow down or stop so it doesnt mater if the turbo ends up spinning a couple rpms faster. also, the sound it emits when vented to the atmosphere is great and scares alot of people. i let eric borrow it to go to the races a couple weeks ago, and after hearing it, no one would race him. plus, when you want to egg someone on on the interstate with no traffic, nothing grabs attn like a bov venting to atmosphere.