Guys.. I've been trying to hunt down the size of my rotors for 3 days now, and I cannot find ANYTHING on it.. I've reviewed the documents given with the car, owners manual even, NOTHING.. I need to know the size rotors (ex. 380mm front or 400mm front, 356mm rear) this car with the 4.2 V8 engine comes with. I'm in need of new brake rotors and pads, and want to step it up a bit to a sportier look.. Please help, will be greatly appreciated.

 

I had to measure mine just make sure. I took a piece of thick paper (posterboard) and cut an 8" half circle out of it to clear the center part where the hub and wheel studs are so it would fit flat on the rotor face without bending. Holding it exactly to where it covers half (along the diameter) of the rotor, I marked the outside edges of the rotor. Then measured the distance between the two marks. Since the front rotors sizes are 20mm apart, it's not going to be hard to confuse which one you have. If it measures within 5mm of 380mm, it's a 380. It it's close to 400mm, it's a 400. Also note the number of brake pads in the calipers. Some use 2, some use 4 on each caliper. My 03 A8L has the 323mm, 4 pads per caliper setup.

Update: It appears that your car only has 2 pads per caliper on the front regardless of the rotor diameter. The 400mm rotors are the Brembo flavored ones. The 380mm is probably the stock setup (probably Girling or ATE).