Skinny downpipes and Cats begone with you!

[lemond]

Ah yes the warrant only applies to original owner.... I bought the car with it fitted too!

I bet a fabricator could add you some more stainless (304L) and then fit a bracing plate too.

As for the cats anybody know the ID and length of the Milltek cats for S4 or RS4?

[tdiquattro]

RS4 main cats are 200cpi. pre cats are 400 AFAIK.

Sorry for the confusion Mark mate, thanks very much for the reply but I meant the physical dimensions, just to get the right size 100 cell race cats for the job.

Any one know the original size of the RS4 ones? and if the 100 cell ones should be bigger / same size, etc, I don't know the theory of the gas flow, emissions reduction verses size, etc.

Cheers

Nigel.

[MarkB]

Ah OK. I can measure the RS4 cats for you if you like. I have a pair of downpipes sat on the garage floor.

I would think the 100 cel ones would be the same size just not giving the same amount of filtration. Should still pass MOT though

[lemond]

Not only do foil cats have less cells per inch (eg each cell is therefore bigger and less restrictive), but they also have a thinner cell wall as the foil is much thinner than the ceramic, so more actual flow area.

Also I think the ceramic cats have to have an intermediate layer (like a metallic wadding material or something) of some gubbins which is no good for flow so their overall dims are even larger relative to their actual useful x section area for flow.

[tdiquattro]

Just bought a pair of these...hope they fit!

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... mot_widget

They look about right, I paid 110 euro each plus postage,I will see how things go and let you know.