" Some eye popping numbers here from a B5 S4 running twin Garrett GTX 2867 .63AR turbochargers at ~33 psi. The dyno numbers from the Gintani Dyno Dynamics dynamometer which can record output at all four wheels. The owner says he thinks he has about maxed out the turbochargers and has tried roughly 15 different sets of turbos settling on the GTX 2867. In additoin to the turbochargers he has aftermarket cams and solid lifters which explains the 8000+ rpm redline.
The 714 wheel horsepower number is with meth injection and is the high boost figure. It certainly does appear to lag quite a bit not spooling until the 5500 rpm range. So lag, lag, lag, and then hold on for dear life.
The pump gas + meth figure is 615 wheel horsepower at 27 psi. This is definitely a strong B5 S4.