Audi Quattro S2

[Colin Plit <richmond@iafrica.com>]

I own a 1991 model. I am told that there are about 50 cars in South
Africa.
I have experienced problems with the turbo. 
The car goes fairly well, but lacks the "kick" you normally get at about
3500 rpm.
The Audi dealer thinks I am imagining it.
They have at my expense:

1) Serviced the turbo and wastegate.
2) Replaced the air flow meter.

They seem to either have no means of comparison or do not have the time
to find the problem. They say that all the electronic readings from
their equipment indicate normal operation.
I would like to make contact with owners of S2's and also technically
minded people who may be able to help.