I already have a cat back exhaust on my 2001 a6 2.7t. I was thinking of either removing the cats in the mid section or gutting them. If i do this i will definitely get a code right? What has to be done to get rid of the code and still have the cats cut out or gutted. I need some opinions on what to do please. Any advice is greatly appreciated.

 

http://audidiy.com/b5s4phps/b5s4exhaust.php

its from the b5 s4 section but its the same thing. you can use de-foulers from autozone, but jhm and vast sell ones too($$).

 

What exactly are de-foulers and does it matter where I get them as far as quality? Where do they go do they replace the 02 sensors? And also I was just going to gut the secondary cats. Should I also gut the pre-cats?

 

the de-fouler is a spacer for the o2 sensor. the o2 sensor goes into the de-fouler which goes into the o2 sensor bung. they space the o2 sensor from the extra exhaust gasses that will cause a cel showing a faulty o2 sensor. they dont work all the time though. the ones from jhm, vast and rai will work perfect, but are a little more expensive.

gutting both will get you the best results as far as sound and power go. not sure how emission friendly this would be or if only gutting one or the other would make a difference.

 

Ok, the pre cats are after the downpipes right? Do the downpipes have filters in them too? If its not too much of a pain i would like to free up all the pipe I can. Basically I want to save money here because downpipes are too expensive.

 

pre-cats are in the down pipes. the secondaries are under the car. gut the pre-cats for sure. this will help you spool better and takeaway some of the heat build up the cats cause. spending $1100+ on down pipes is ridiculous. this is a great mod. have you seen the ss autochrome downpipes? theyre like $300 and are larger. auto or stick?

 

My car is a manual and I haven't seen the ss chrome downpipes. How are they? I was also looking at these from vast performance. The thing is I need someone to do the work on my car because I cant weld and I dnt have a lift. And all the shops ive been to around me cant take the cats out because of the law, so.....




https://vastperformance.com/index.ph...-2-7t-360.html

 

Yes it happens, just be happy it didnt cost you the over $1000.00 dollars it would have with out a warranty.

 

The Vast Piggies are good stuff, basically its exactly what you are saying you want to do by gutting the pre-cats. The Main cats are not gutted. Infact, most people do not gut the main cats from what i've heard, if anything they'll just weld in straight pipes, but gutting the pre-cats is a very good bang for the buck. You will throw a code without the defoulers as other people here mentioned if you are planning on going to straight pipes in the cats as well. But if you are just gonna do the Vast Piggies, you wont need de-foulers. Vast relocates the rear O2 sensor behind the main cat so it does not throw a code.

 

http://ssautochrome.com/level.itml/icOid/1895
here ya go. you can get them separate from the cat-back. they are good quality and cheap too. the vast piggies are nice but waaay to pricey for what they are. $400 for them to remove the pre-cats and re-locate o2's is crazy in my opinion. the ss autochrome dp's are cheaper and will net you more power gains. i think there is a group buy on audizine going on. they just came out with a re-vamped set-up. these are basically copies of awe tuning dp's.