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100cpi is (100 cells per inch) less filtration, so more free-flowing, likely to light up the engine management light on the dashboard and emissions could fail MOT, also noisier, may have implications on fueling/air mixture confusing ECU - but I couldnt say for sure .

200cpi - the more accepted one - will not affect Engine management - more expensive, but quieter, usually better quality manufacturers make these.

if you are going for all out noise from the exhaust then 100cpi - otherwise if you can afford 200cpi

all the best
David
 

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42000 miles on a 100 cpi Magnex sports cat and no engine light problems for me! Ill let you know about the emissions test next March! The ST has a quite advanced ECU and sensor set up that adjusts for differences in the components of the exhaust and intake system! Fitting a de cat will bring on the engine light but will not affect the mixture unduely! The same goes for whatever cpi cat you run! The 100 cpi is not noisy at all! In fact i cant really tell much difference soundwise to the standard cat! It is a bit bassier though and you get more pops and bangs as the fuel thats dumped to cool the exaust valves is much freer to explode with a 100 cpi!
 

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100 cells per inch is better than 200 cells per inch as less cells = less restriction to the air flow.
A decat is zero CPI (but not road legal) and a standard ST Cat is 600 CPI.
 

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I stand corrected

the 100cpi cats have improved lately then.

although I dont agree that 100cpi is BETTER than 200cpi

the 200cpi as far as I was aware from research was made for road use (100cpi initially designed for those doing track days in a road legal car - and from being in ST's with 100cpi cat - they are definately louder - with more pops and bangs than the 200cpi fitted to mine)

you pays your money and takes your choice.
 

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QUOTE(woodside @ 12 Nov 2009, 09:59 AM) <{POST_SNAPBACK}>although I dont agree that 100cpi is BETTER than 200cpi
IMO the 100 CPI is better, the reason for this is because the 100 CPI Sports CAT gives the best gas flow possible from a road legal catalyst.
The performance difference between a 200 cell and 100 cell are minimal though.
 

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Hello,

100cpi is perfectly acceptable for a MOT pass, try and get hold of a copy of Fast Ford June 09 edition, and that explains almost everything about exhaust systems
 

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100 CPI mongoose passes MOT emission test
200 CPI i suppose is a compromise between power and refinement, but 100 CPI isn't that loud. The whole thing is puny 86db in fact.

I had full system for quite a while now and every time i drive std car i want to run back to mine for everything, including noise.
 
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