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Discussion Starter #1
Hi all,

Is it worth fitting a sport or race cat to my Brera 2.2JTS? It already has a cat back straight through system including Vortex silencer.

Is it likely to fail MOT after a cat replacement (it's 2.5 years old)?

Also what kind of gains do you see - small I expect, but are the gains throughout the rev range or only at top end?

Cheers.
 

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Sports Cats with 200cpi are said to pass MOT tests. If you fit one with less Cells Per Inch then it will fail.
 

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Waste of time IMO

may change noise but that's about all
 

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Sports Cats with 200cpi are said to pass MOT tests. If you fit one with less Cells Per Inch then it will fail.
Not necessarily - GTA's pass MOT tests without the main cats (still got the manifold cats) and will definately pass with 100cell cats.

I'd expect to see gains, not much, but you should definately see an improvement in its willingness to rev. My Elise was improved massively when the cat was removed, felt far more "laboured" with it fitted.

My decat is being delivered tomorrow and fitted on Sat, so time will tell ;)
 

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Waste of time IMO

may change noise but that's about all
total disagree with this statement!

ive upgrade my exhaust system, and on my 2.0l GTV CF3 engine a sports cat made a noticable difference.

the engine is a lot more responsive at low rpm and the torque is much higher. i would recomend it,

after fitting mine it had a MOT a week later passed first time.

P.S. i have the alfaholics system if you wanted to no what exhaust i have.
 

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There's a test floating around somewhere where back to back tests were done with standard, none and sports to see which offered most power.

Standard came out top, I'll have a search for the file...
 

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I think you need a remap to feel the differnce, otherwise the gains are small.

regarding emissions, I passed these stages:

1) everything original - perfect values, what would you expect :)

2) removed precats on the manifold, main cat kept original - emission values like in the first case, everything fine

3) removed precats on the manifold, single main cat replaced with 200 cpi - emission values like on a cold engine (engine was heated up after 15km drive, but about 10 min on iddle before test). When I hold the engine at 4k rpm for about 30 seconds to heat the main cat back up, we could measure acceptable values to pass the test :)

Car was remaped after the precats removal, so it might have changed the values as well.
 

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Discussion Starter #9
I was told by my fitter that in the UK, for cars younger than a certain age (2001 I think) you can't change the cat without going for a special approved cat or something?

Are they right?
 
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