L series turbo adjust

Hi has any1 adjusted up the turbo on an L series 2.0L td (pre td4), i was nephew mechanic and after looking at the turbo it is adjustable, does any1 know what the standard setting is (max min middle) etc? and if any1 has done this is there a good gain to be had?..

I have now adjusted (well the nephew has) up the turbo to its max and there is a noticeable difference on an hr run with medium to high revs the temp gets a little hotter but not much, maybe a couple of mill higher on the needle so I’m not going to worry about overheating and all’s good..