Well I just got my A4 2.0T 2009 premium plus today, and I drove it for about 3 hours. I am very pleased about the car but I think I might have overpaid. I got a 4 year warranty and it was a certified Audi with 35k miles on it. I just wonder what kind of things I can install without voiding the warranty?

I used to own an A6 2.8L 2001 and it was a nice car, I had a K&N filter on it and it was great and I am thinking of adding that to the A4, is that fine? Maybe after 4 years install APR tunes.

Also I know that I have to use premium gas 91, and I am fine with that. But today I noticed when I went to BP, the gas station had Ultimate 93, 89 and 87. I used 93 because I would think thats the "premium". Is that fine? I do not want to damage the turbo.

Any other quick hints for a new owner would be appreciated!!

Thanks