i have a 2000 a6 2.7t. and my cat is throwing a code. i belive it is bad. i am getting bad gas mileage, it feels bogged down, and today when i went to get onto the freeway today it started to sputter and didnt want to speed up. so i was wondering if i could cut the cats off and just weld a couple straight pipes in place of them. advice is very much needed. thank you jon

 

You may want to try replacing your fuel filter first if it hasn't been changed in a while. Also try running a bottle or two of Techron after changing the fuel filter if that's the route you want to go. Technically you could do it but I think you'll have to deal with the pre-cat and post-cat sensors. You could try to gut the cat converters which would achieve basically the same effect as straight pipes.

 

I recently had the same problem with my cats - so I had them cut out and a straight pipe put in their place. There was a very nice power increase and a slightly different sound now.
The only thing I'm working on now is replacing the rear O2s .. during the removal process they had to be heated up so they could be removed - now the sensors are dead. I had some spark plug foulers welded to the straight pipe and hopefully that will take care of cat codes once I have the O2s replaced.
I will let you know if that worked out once I have the time to replace them.

 

Follow up:
O2s replaced - drove over 200 miles and set readiness. No codes yet