Hi mate,
Nice beast.
I personally dislike the arrangement with only one needle and one dawes, as it is not efficient in terms of managing our VNT turbo.
I did try it, but preferred to add a second needle behind the dawes, and setting the dawes in such a way that it would open at +300mbar boost. And you act on the second needle to set the max boost as you wish. Otherwise, all you can set is spool-up with the first needle, and the max boost at which the dawes would open and open the vanes suddenly. In between, the vanes stay closed as set by your needle Needle.
I have now done it with electronics and software which allows any setting, and, in particular, a proper setting to get our Patrol to run beautifully at any altitude, whether it be at the sea side, or on top of the highest driveable montains., without changing any setting.
Cheers,