What to expect from a decat?

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cammage08

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Looking at fitting just a decat to my S3.. I know a downpipe would be a good idea too but im happy with the S3 as it is.. managed to get the decat very cheap so I thought what the hell. Other than the MOT will i have any other issues like eml or anything?..... or should I just sell it on? My S3 is remapped with forge TiP etc.

Thanks
 
Id be very interested in your opinion of the decat once you have fitted it. I simply cant be bothered with going downpipe either so please update this when you have fitted it.
Are you using oem cat back?
And i think i read that eml light depends on your engine code
Bam and amk will bring a code apy wont but id wait for confirmation on that, just something i believe ive seen in the past.
 
Well my engine is a Bam... can somebody confirm it will bring the eml light on? The decat pipe has got the lambda probe port so i will be using it. Yes the rest of the exhaust is standard for now...
 
cammage08 said:
Well my engine is a Bam... can somebody confirm it will bring the eml light on? The decat pipe has got the lambda probe port so i will be using it. Yes the rest of the exhaust is standard for now...
Click to expand...

If it's a BAM, it will most likely bring an EML light on. On my car, a decat with standard downpipe and exhaust released around 10 horses!
 
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Hmmm i dont really want to run with the eml light on... can this be mapped out or adjusted?
 
Yeh it can. Also there are spacer pipes that trick the car into thinking the cats there.
 
audi upgrades
So is this what you are still running jojo?
 
I get it...So it pulls it out of the pipe so to remove it from the flow of gasses a little to trick it... Ye my decat is getting put on tommorow, but wont be able to test until weekend as im working away until then. Found some spacers on ebay, what size is it i need? M18?
 
On my a3 it made a lot of difference, the low end torque was increased quite a bit and the turbo seemed to spool up much quicker. The cats on the quattro cars are massive restrictions
 
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Jojo. Sorry i wasnt clear. Thought you had full downpipe and decat?
Or do you still have decat pipe only?

I had a decat on my leon cupra 1.8t years ago and it was really good gains. Sounded good went noticably better but not many using decat only on s3's
 
daz-20vt said:
Jojo. Sorry i wasnt clear. Thought you had full downpipe and decat?
Or do you still have decat pipe only?

I had a decat on my leon cupra 1.8t years ago and it was really good gains. Sounded good went noticably better but not many using decat only on s3's
Click to expand...

Decat only mate, I'm not into the whole exaust manifold and downpipe tuning, I prefer OEM as much as possible, which is why I'm still running side mounts on my car.
 
Decat fitted... I'll post my thoughts friday/saturday when i get home and a chance to drive it.
 
Only just seen this... I've been running one of those spacer eBay things for about 3 weeks with a decat - no EML or any fault codes :D
 
The only thing that worries me is getting pulled over for an inspection.. I'd read the fines for running a decat are pretty high now days.
 
Ye there is always that... but my S3 looks completely standard. I run a full straight through exhaust and decat on my 106 rallye that looks and sounds like it should only be on a track and ive never had anyone look or check it.
 
So how did you measure the 10bhp jojo?
On a rolling road or airflow?
Also did you notice any gains in the way it drove?
 
daz-20vt said:
So how did you measure the 10bhp jojo?
On a rolling road or airflow?
Also did you notice any gains in the way it drove?
Click to expand...

Average RR printouts from RTec and Bills rollers, turbo spools up a bit quicker and there's a small gain through the rev range. More boomy at 3k revs though.
 
Had a few trips in the car since the decat and all is well.. seems to boosts earlier. Theres alot less hesatation and just generaly feels smoother. No eml yet but will i need to do a full scan to find lambda faults?
 
when I fitted decat to my A4 it took about a week for the car to realise the levels were the same and chuck on the elm
 
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Nothing, just leaving it at the moment until I get an exhaust system fitted and get a remap
 
So would you say worth a buy?
How does it sound now?
 
I would say it's worth fitting one but it's personal preference to be honest. Fit one and if you don't like it, remove it. Mines really easy to get to if I wanted to remove it. I might not keep it when I get exhaust system fitted it all depends. Not really much sound difference, only from cold start you can hear it burble as the SAI is running. But you can hear the turbo spool and it kicks in sooner too
 
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Ye ive got a nice burble at higher revs when changing gear.. and ye generaly sounds nicer I think. I got my pipe and fitting for less than £100 so a cheap modification in my eyes.. just waiting for the engine light to come on!
 
That's a bit pricey, mine cost nothing to fit but it's only because I know the owner of a local garage. Can you not fit it yourself?
 
I can do most things but didnt fancy rolling about on the floor trying to get 11 year old bolts out of a rusty exhaust! :)
 
Preparation :) get under there the day before and spray some wd40 or something of the sort.
 
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john ashley exhausts is where i got mine from. you c IMG 2172an ask for lamda sensor port to be added. Had it fir a few months now with no problems.
 
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Thinking this as well but I will need the ****** thing for mot..I don't know anyone who would pass it illegally..
 
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