Jim;
    The type of van means far more for ambient noise than most engine
choices, as long as the exhaust isn't a goat rope.  Passenger vans are far
quieter than any Westy.  Syncro passenger vans included.  Db meters mean
nothing unless it is the same type of van. Passenger vans have factory
sound insulation all over the place, Westies have none.  I tried to
replicate the passenger van insulation in my Westy.  It helped but not
even close in quietness.  FIberglass top wind noise maybe???
    SVX engines with stock gearing are loud on the highway.  With a .70,
it is very pleasant and muted, with a mild, pleasant, 911 sound. You can
barely hear it at 70-75, and the wind roar at the more normal 80-90 far
exceeds the engine noise. I have been without a SVX in my personal Westy
for almost a year.  I miss the sound every day I drive it. Around town
they are a slightly louder, but it is a good loud.  I never minded it.
Locals in WA an CA always did a double take when I pulled in or out of a
parking lot.
    SVX's were a very limited production engine and are not for everybody.
Most are now 15 years old.  Parts are not as common as 4 cylinder Subies.
But then again, Vanagon parts arent all that easy to come by either,
resulting in this list.  I think I see more SVX's in PA than Vanagons, so
maybe it is not something to worry about in that context.
     All that being said, our SVX shop installed price is only about 1500 -
 2000 more than a late model 2.5.  A turbo would be 2000 dollars more than
the SVX. MPG is about the same, maybe very slightly better for the turbo
motors.
     Did I mention I miss my SVX engined van every day?

     John
     Vanaru.com