The 1991 200TQ with 20V Turbo Engine was designed to run a maximum of 1.825 bar boost (absolute) or ~12 psi gauge pressure, as set by the Motronic Engine Control Unit (ECU).

The 1992-96 Audi S4 in overboost mode will have boost set to about 2.15 bar absolute. The actual boost produced will vary depending on engine RPM, air temperature, fuel quality, and altitude. The 20V boost control system is different than what was used on the earlier 10V Audi Turbo engines.