I just spoke to a friend that has the Audi S3 and he has de-catted his exhaust in a way to avoid dealers detecting it (of course they would hear it tho)

Here is what he did:(im not so clued up so i will try explain as best as i can)
He opened the existing CAT and removed the stuff inside then re-welded the CAT back on, so from the outside it looks 100% stock BUT it sounds INCREDIBLE now.

Do you guys think this would work on an R56 cooper S?
YOu think i would get CEL's????

 

There's a company in Uk that do just that!
You can either fully decat it by removing it all or partially de-cat it by removing only half of it's guts in UK we only have 1 large cat whereas you US guys have 2 smaller cats afaik so this could work well by removing one of them.

 

I had my second cat and resonator cut out and still passed emissions testing. If you want to keep the OEM look then just disconnect at the downpipe flange and beat that second cat with a pole or crow bar. If you mess with the downpipe cat you'll need a o2 sim to fool the puter or you will get a CEL.

 

okay interesting, im actually in SOUTH AFRICA! LOL. but yes we have 2 smaller cats. im going to have to look into this. I spoke with powerflow (our local exhaust shop) and they rekoned they couldnt do much to it. They said it would sound the same if i messed with the backbox etc. they were hesitant to mess with the cats. I must also look into getting the 02 sensor thing sorted if i manage to mess with the cat in the downpipe. We have NO submission Laws so we can do whatever we want here...

 

I find that its best not using o2 sims, ive had the ragazzon catless downpipe and now the atp catless downpipe and both had the o2 sensors plugged back in as normal and i never got/still dont get a CEL

 

Its called "gutting" the cat. Its VERY common in alot of other car scenes. It's not so great though because cats arent cheap. But what you do is take the cat out. Get a pipe and hammer and hammer the heck out of the honey comb till it all comes out clean. Some times you have to use a drill to get it started....

 

If you do tha tto the first cat you will get a cel for sure. The audis have had tunes for a while so they can tune it so they dont get a cel.

 

FYI the MINI cats(along with most imports) fetch a good price at a cat recycler(I got $150 for mine) so if you don't have to kill it you can make some quick cash.

 

air chisels work great to get it started....there is no reason to open it and then weld it shut. just get a long bar and start hitting the heck out of it. this worked with a subaru exhaust but the mini will throw a CEL for sure.

you might as well trick the dealer by buying a exhaust to get rid of the cats and then when your taking it to the dealership put the stock stuff back on.

 

Dealers don't care...the government does.

Plus, the dealer will SMELL your car right away and it will be very evident from the smell/noise that it is catless. If you're going to go catless, just go all the way and put a full straight pipe in there.

 

whats the difference with a straight pipe?
more noise i presume, and more emissions, but does it drone alot more also?

 

CEL will come. There's not much power to be gained by removing it, oem cats in general are pretty efficient. (coming from the VW world)

Here is a way not to have to cut your stock cat up-
http://www.siliconeintakes.com/produ...c1f9039b854fb9

 

Gain 10-50 horsepower just by switching your stock catalytic converter to this amazing product.This product should only be hung on your wall to express your rebellious nature, never installed in a vehicle. This product may cause cancer. This product is actually a water pipe.

 

As much as i want my cooper to sound awsome! seems that i cant obtain it (unless i drop my motorplan which is abig no no) so guess i will just leave it as is (altho the cone filter does do wonders with the "psshhh" sound and the turbo spooling ) think i will just work on the outside look of the car, its just difficult tho because ALL my cars have always had beautiful exhausts on them.thanks for all the help guys, i mite look into "gutting" the cat see if its not too risky...

 

No offense but people have been doing that since catalytic converters came out. If you live in a state that doesn't require an inspection of any kind go for it. But be aware that if you live in a state that has any kind of inspection and they find out that you gutted the cat they can and will fail you on that inspection and if you are pulled over in any state in U.S. and they find out that it is gutted they can impound your car because have a cat on the car is federal law no state.

 

no problem, im in South Africa, no states just wondering if im going to get a cel or not...its a big risk to loose my motorplan

 

dead thread resurrection.

I gutted the second cat on my 09 MCS and freakin love it. Stock muffler sounds much sportier, but no drone. No CELs in the past 5k miles... Keep in mind this is the second cat, not the downpipe, there are no sensors after it. As for performance, the DP cat is probably the limiting factor, but it's worth the hour work for the sound alone.

My process was pretty simple. I dropped the exhaust after the DP. I cut the exhaust just behind the cat, as if I were installing a cat back. I then drilled and chiseled out the cat. I used a coupling from the local auto store to put it back together.

 

For the effort just have a custom pipe from the dp to the muffler that doesnt have a cat. Unless you are in warranty who cars what the hell the dealership thinks. JCW exhaust FTW because it takes out the 2nd cat.