The factory adjustment is made using a gauge that measures

pressure (or vacuum, I forget which) that is required to start

opening the wastegate. Presumably, it is set by hand so there

is some variation. I have seen a report here by someone who

noted it was not a bad idea to really measure it and make sure

it is at the prescribed factory settings (but most people just

twiddle with it and don't actually make any measurements). I

would conjecture that settings drift a bit over time as the

parts wear or break-in, too.

By the way, on my 98 S70 T5 3 turns did not really make much

of a difference at all. I did not push it past 3 turns.