From what I've seen they run low 14s stock with the 6-speed... not too shabby for a damn nice luxury sedan
With the mods you listed: Chip, intake, boost controller, it wouldn't suprise me to see it mid 13s. Oh and The S4 has mad aerodynamics... something like .26 : for those of you who don't know abt this, the lower number of drag the better. Something to compare to- the Supra has a drag coeffecient of .32