Fellow Audi Enthusiast:

I am interested in purchasing a pre-owned Audi A4 2.8 and wondered what year was the 5-valve per cylinder technology introduced on the A4 2.8? Also, what is the factory Audi warranty and are there any recalls, model years to avoid, or things to look for? Last, are there any disadvantages of buying from a non-Audi dealership other than "...a certified Audi"?

Thanks in advance for your assistance,
Andrew