I have a Turbosmart DV for my 95 WRX and have just taken it apart to clean it. I noticed that other than on o-ring seal on the main body it doesn't appear to be sealed anywhere else. I have had my suspicions that this DV has been causing slightly lower boost levels so decided to connect some vacuum pipe pipe to it and blow down it to check for leaks. I found that the air does in fact leak out through the trumpet on the DV (although only slightly but enough to blow a lung full of air through it).

Should this happen? In my mind I would have thought that it should be totally sealed to stop any boost leak.

Can anyone clarify this?

 

It should not leak if the valve is closed.

 

That's what I thought.

Fortunately IIRC the DV has a warranty with it and as I purchased it from Scoobyclinic I am sure they will have no problem sorting it out for me.