I have an A6 as well. I added a Cat back from spintech the sound was very different I really liked it. If you are talking about adding a cat back system with an a6 the afm is something you will need to address. The sound of the afm kicking on and off nearly drove me insane. The car was tuned in a week after I did the cat back. The tune eliminated the afm. you can see nice gains from a tune and it will get rid of the sound of the afm but it will also void your warrany
The American Raicing headers exhaust does not drone at all a few of our guys have them its an excellent product plus its 100% American made kind of rare these days. It also sounds pure evil at wide open throttle
Drone didnt bother me driving around town and short trips but when I went to BBOMG 10 hr trip the drone was annoying.
Of course if you going with an axle back most of what I wrote will not be an issue
The GM exhaust I believe is made by borla
Im actually adding ARH axle back soon myself
Last edited by mucker15; 01-03-2012 at 09:14 PM.