GT, everyone thinks that their tuner "knows what he is doing" at least until somewhere down the line they get to know better !

I apologise, I was lumping you in with all the other "rolling road magicians", I had forgotten that you had a Sportec conversion.
Sportec are fairly unique in the way they do indeed seem to be able to use a combination of good airflow on a sub optimal (in loading terms) chassis dyno (is it Bosch FLA ?) then a large dose of real world turbo tuning knowledge to be able to make packages which do work on the road. That is very interesting what you say about adjusting the boost on the road to allow for lack of dyno loading...

As you say your acceleration numbers (0-300 in ~24s was it ?) tell the story....

The only thing to be aware with Sportec is that the numbers they get (paricularly torque) are usually on the high side - I know of cars measured by their machine have subsequently registered 10% less on Manthey's Maha - but the actual size of the dyno numbers should not matter if the road performance is there.