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      11-12-2013, 12:49 PM   #1
duchozen
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Downpipes Q&A

Hey all,
I have been looking to install catted DP's on my F12 M6 but still haven't fully understood all the factors the consider when choosing which brand.

For example, what is the difference between the Super Sprint catted DP's and the AMS? I noticed the "200" and "300" being tossed around but not really getting what they actually mean.

Thanks in advance!
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      11-12-2013, 01:31 PM   #2
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The "200" and "300" are cell count numbers, referring to the density of the catalytic converter. The higher the number, the more cells per inch, and so the better the catalyst will clean the exhaust gas. Conversely, the more dense the catalyst, the more restrictive the catalyst is to exhaust flow. Most OE applications range from 600-1000 CPI.

The CPI count is not the complete picture, however. By cleverly packaging a very large catalyst in the available space, a downpipe manufacturer can have a relatively high flow catalyst design with no check engine light due to the overall higher amount of catalyst material. Picture a 1" diameter tube full of 800 cpi catalyst material, vs a 5" tube full of 600 cpi catalyst material. The 5" cat would do a better job at filtering exhaust gas even though it has the lower density.

I hope that helps a bit!
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      11-12-2013, 04:19 PM   #3
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Nate, thanks for the explanation. At the risk of revealing my total ignorance, is the only advantage of going with aftermarket catted exhausts gonig to a lower CPI? What is the CPI of the stock downpipes? How much more flow (with through lower CPI or better efficiency) do you get with an aftermarket catted downpipe?
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      11-12-2013, 08:52 PM   #4
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less restriction = more power. If you some of the treads their are a good amount of people that have catted and non catted DP. Non catted will throw a check engine light. There are discussions that are popping up that the 200-300 cells are also sometimes causing a check engine light. Read all the post so you make the right choice for your application/needs.

There is a DP that is catted that has been used by about 6 people that i know of in the USA and has not thrown a CEL to date . I purchased the said set while in Germany. I have not had it installed yet because my car has not arrive back from my ED. The price of this set was in line with all the others. It is a 400/300cel vs stock 600.
http://www.noellemotors.de/produkte/...r-s63-tue.html
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      11-12-2013, 10:44 PM   #5
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You need to get here and install that bad boy so I can hear it in person before I leave out again.
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      11-13-2013, 08:58 AM   #6
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Quote:
Originally Posted by boots
You need to get here and install that bad boy so I can hear it in person before I leave out again.
Working on it.
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      11-13-2013, 09:50 AM   #7
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Boots, just fly to DC and come hear my straightpiped badboy in person.

Track Day in a week and a half with Full Straightpipes, gonna be epic!
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      11-13-2013, 10:33 AM   #8
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Damn wish I could Dave. I know I would have a good time. I need to hear your exhaust in person. I didn't even get a chance to fly to Cali to meet you guys up there like I planned. All my plans to do something for vacation were messed up by uneventful stuff. I return offshore next week for prob 30 plus days
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      11-13-2013, 12:57 PM   #9
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Quote:
Originally Posted by RPiM5
Boots, just fly to DC and come hear my straightpiped badboy in person.

Track Day in a week and a half with Full Straightpipes, gonna be epic!
Any noise restrictions at VIR?
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