I don't think they will help reduce noise from the vent window.  The
deflector sits above the roll down window.  They should reduce noise
with this window cracked.

Now on the EuroVan, they reduce wind noise around the mirrors, but the
EuroVan has no vent window, and the deflectors extend to the front edge
of the glass.

Steve
http://EuroCampers.com
636-337-7700
888-797-5994 - order desk
On Dec 15, 2007, at 8:24 AM, Stephen Edwards wrote:

> How do these deflectors affect wind noise? For years I've had to get
> out of the van to properly close the vent windows, or else run with
> them slightly cracked, in order to avoid irritating whistling sound.
> Do deflectors help or hinder?
>
> Steve Edwards, 91 GL with Subie 2.2, Chicago
>