Oh no...not this again.
You do not need one. Unless you are running BIG horsepower...over 300 BHP for example.
There is no proof that running d/v's prolong the life of the turbo..but similarly, there is no proof that not running one shortens the life of the turbo.
That's about it really in VERY short form.
ADMIN: Can we have a D/V Sticky topic explaining all (seeing as the search function is dead & we can't re-direct people to particular threads) ???