Audi literally covered all bases when they released the RS4 in saloon, convertible and estate formats. Sonorous V8 is a gem of an engine. One of the last manual transmission super saloons.
PistonHeads Audi RS4 B7 Buyers Guide – A good additional reference to use alongside our article.
MTM Tuning – Remaps and other performance enhancements for the B7 RS4
RS4 B7 vs M3 E46 CS Fifth Gear Review