Audi’s S4 is one of the best performance four-door family cars you can buy.Elegantly styled, with a comfortable cabin and rampant performance courtesy of its supercharged three-litre V6, the S4 really is most things to most people nearly all of the time. If you would like something a little extra, the opportunity to turn your S4 into a B8-series RS4 of sorts, then American tuner STaSIS engineering has the solution. STaSIS engineers at its workshop at West Virginia’s Summit Point racing circuit have fashioned two upgrade packages for its S4 signature series: Touring and Challenge editions. The Touring lowers Audi’s factory S4’s ride height by 25mm (lowering its centre of gravity) and increases the spring rate to improve reduce individual wheel oscillation over imperfect road surfaces at speed. QUAD EXHAUSTSStaying true to its name, the STaSIS Touring edition is very much like a touring car racer for the road. It has all the Challenge’s modifications while adding upgrades brakes (390mm discs and six-piston Alcon callipers), a high-bias centre differential and Ohlins shock-absorbers. With regards to engine modifications, both Touring and Challenge edition STaSIS S4s feature similar upgrades. Quad exhausts have been added for acoustic appeal and better gas-exchange efficiency with relaxed engine control parameters bumping up peak power and torque to neat round numbers of 300kW and 500Nm - improvements of 55kW and 60Nm over the factory S4. STaSIS says its S4s will run the 0-100km/h in less than five second threshold, with the Touring edition’s suspension and differential modifications enabling it to pull a full 1g on a skid pan. Prices for these modified S4? Packages start at the equivalent of R145 000.