I recently purchased a 2005 A4 1.8TQ but am a bit confused about the model. While looking the car over I noticed the front rotors are drilled and the front brakes are much larger then the rear. I don't think the previous owner did any modification, so do these larger brakes come standard on certain editions? How would I check the suspension and what would I even be looking for? I'm 90% sure it's the B6 style and the lower trim is the same color as the rest of the car.

Also when I have the windows open the radio volume changes loud and soft quite frequently, how do I disable that?

 

It's standard for the front brakes to be larger than the rears by a significant amount. Drilled rotors are not standard, but the previous owner may simply have had to replace the rotors at some point and opted for drilled rather than plain.