I managed by incident to find a MAC-11 unit with a QLCC installation advise for the following wastegate spring as well.
Haven't got my hands on the items yet, but will soon, and thought about asking in here if anyone had any good highlights/details about this hardware?
I take it there are minor adjustment in the PROM to allow for a different ingition timing table, and a boost limit raised for approx 0.95BAR together with a 2BAR wastegate spring.
I did find this: http://www.audifans.com/archives/1998/03/msg01434.html
Ben Swann's homepages seems to have gone away though...