The links at the bottom of the page are to a pair of tunes that I evaluated on a DynoJet the same day using my B5 S4.
There is a Nefmoto K03 Stage 2 community tune that was the product of a community tuning effort as part of a training discussion.
There is also a more aggressive K03 Stage 2 tune, referred to as the Notorious VR Stage 2++ tune on Nefmoto.
A comparison of these two performance tunes, along with the stock Audi B5 S4 tune, are shown below.
The chart above is for the manifold boost pressure that each tune generates, the lowest being stock, middle the Nef tune, and highest boost generated by the NVR tune.
In the chart above is shown approximately where each tune operates on the BorgWarner K03 compressor map.
The IDC chart above is of the respective Injector Duty Cycles for each tune.
Below are the Uncorrected DynoJet numbers for wheel horsepower and wheel torque:
The links below are to the binary files that I have loaded onto my B5 S4 and that were used during the dyno session.
There are no guarantees that your S4 will perform like mine if you use these tunes.