gutting cats on s6?

**pismojeff** · 09-30-2010 09:04 PM

anyone done this? I am getting a CEL from a bad cat that comes up every once in a while and thinking about having my shop just gut them... need to know if anyone has done this on the S6 and if they have a kit to get around the CEL that results from this. I know they make them for your 2.7's but was not sure about the S6

thanks

**ChescoS6** · 09-30-2010 09:15 PM

Or you could just cut them out and replace with a pipe fitted with a bung for O2 sensor and anti fouler. I don't see a problem with gutting them though. I plan on having mine removed when I do my exhaust.

**4ringAR** · 09-30-2010 09:21 PM

just use O2 sensor spacers made from spark plug non foulers. No need for a "kit"

BUT if the actual O2 sensor is bad, then this isnt going to fix your CEL. That happened to me when I gutted teh downpipes on my 2.7t that had O2 sensor codes...but hey, now I have gutted downpipes which I had wanted to do anyways!

Chesco--I imagine he means the pre-cats are bad.

**pismojeff** · 09-30-2010 09:22 PM

yeah, I don't think I will do full exhaust unless I keep the car a while. just trying to get around the CEL and add a little sound/performance

**pismojeff** · 09-30-2010 09:32 PM

yeah the CEL is from a bad cat, not a bad sensor... I will see if my shop knows this method you are speaking of. still hope to hear if anyone with an S6 has done this

**pismojeff** · 10-06-2010 09:59 AM

ok, this is what I got back from my shop. let me know what you think:

"Removal & replacement time for your catatlytic converters (Standard Labor Time) 3.5 Hours/ $315.00

We have a few options for replacement - We can either:
1 - Save your exsisting cats & have Shane @ Custom Exhaust Specialties, fabricate NEW Cat-by-pass tubes w/ the j-pipes for the 2nd O2 Sensors. - Addition fabrication time from Shane.

2 - Gut out your existing Cats - Cut them open & remove the catalysts material & re-weld the units. Then attach the j-pipes for 2nd o2 sensors and re-install. - Additional time for cutting cats open, hollowing them out, re-welding units & install j-pipes for replacement is expected to take between 1.5&2 hours to do both Banks. = $135-$180

What do you think?

Expect total cat-bypass to be around $450-$550- w/ J-pipes purchased & Installed by us."

**4ringAR** · 10-06-2010 10:06 AM

3.5 hours to pull and reinstall? Lol. Something tells me they've never removed the down pipes from and audi v6/v8. I understand they are professionals, but it's a bitch of a job, even with a lift and all necessary tools.

I'd go with whatever option is cheapest, either version of what they are saying sounds good.

**pismojeff** · 10-06-2010 10:08 AM

so you think his time estimate is a little low? sounds good to me...

**4ringAR** · 10-06-2010 10:14 AM

If they will do it for that price go for it, but it took me and a friend 10 hours total to gut mine, and he had done a few other cars before mine.

**SteveKen** · 10-06-2010 12:15 PM

The downpipes on the S6 are easy to remove. I've done it with the car jacked up in my driveway.

They actually do not need to remove the downpipes because the cats can be sawn off while still on the car.

With them out, they can either be re-welded and re-installed (to pass visual I suppose) or straight pipes can be spliced in.

**pismojeff** · 10-06-2010 12:36 PM

thanks steve... glad to hear from someone with experience on this. so sounds like it might even be cheaper if my shop goes this route. did you do this on your S6?

**SteveKen** · 10-06-2010 12:46 PM

No. My cats seem to be good. What's the mileage on your S6? You know there's a recall/warranty that good on the S6's up to 100k miles/ 10yrs. The dealer will replace them for free if you're under this mileage. (search qw for details on this)

FYI, the S6s do not have pre-cats either (one reason why they're easier to remove). So don't let anyone sell you on gutting your precats or special modded code for gutted precats, etc. since you've already got them.

EDIT: here's the link: http://forums.quattroworld.com/a8/msgs/14131.phtml

**pismojeff** · 10-06-2010 12:50 PM

yeah, actually just about to hit 104K miles... my shop told me about that warranty but looks like I am out of luck

cool, I know my shop is super honest but that is good to know anyways on the pre-cats. I will see what they think about doing the job without removing the downpipes

**SteveKen** · 10-06-2010 12:58 PM

You might be best off just taking it to a muffler shop if you can find one that will do it irregardless of the legality.

**pismojeff** · 10-06-2010 01:00 PM

I am in Bend, OR so I am pretty sure legality is not an issue... I could be wrong though

**8520** · 10-06-2010 01:15 PM

My vote is option 1, but you will need defoulers.

The secondary o2 sensors are basically there just to make sure your cats are still working, so they have little pertinence to how your car is running.