>But instead of letting exhaust gases escape the turbo at low RPMs (like 1.5 >grand) adjusting the wastegate should theoretically force those gases through >the turbo and get it spooling up quicker.

I think that is what it does. Divert enough and the "idle" speed of
the turbo would be higher so lag should be lower. Too much, and the
turbo is probably spinning fast enough where you get full boost with
even minor throttle changes. I would think this would reduce gas
milage and maybe shorten turbo life a bit.

Volvo has a TSB that tells you how to set it to factory spec using a
vacuum gauge. I suspect to compare results, everyone would first need
to verify they are at the factory setting and work from there. Some
may be adjusted a bit low from the factory and others higher (explaining
the different results reported).