hey this weekend i wanted to take my cats off as they are starting to make a clicking noise and straight pipe it... problem is i cant find the size anywhere. i need the diameter as well as the gauge. ive contacted the dealer, 2 in fact, no one knows. Any of you know?? its an '01 A6 2.8

 

Ever consider crawling under the vehicle and measuring the pipe diameter before and after the cats? It's not rocket science.