What rpm should I shift my 1998 audi a4?

hey i have a 1998 audi a4 and the engine is 2.8L. the car is automatic but it has a tiptronic that i like to use... but i was wondering at what RPM does the car perform best at? i think it redlines at around 7,000 but it automatically goes into gear once you go over 6,000 if anyone can tell me when to shift that would be great.. thanks!