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05-05-2020, 01:31 AM | #1 |
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Does any one replace their primary cats with high flow primary cats? especially s/c'd
Hi Guys,
I have a Harrop s/c e90 M3. I have the full stock exhaust system at the moment but would like to switch to a high flow alternative. I am also a bit of an eco warrior (hypocritical I know) so don't want to go the decat route as this is my daily driver. I would like more power (probably unnecessary as there are 490rwbhp). There is very little info I can find about replacing the primary cats other than test pipes. I have found that Cobra make a high flow cat'd front exhaust/up pipe/1st section or what ever it is called. As does supersprint, but I cannot find out any information as to whether this will give me some extra hp, be worth while, terribly affect my emissions. A further option that I don't see why couldn't be done would be to cut out the primary cats and to weld in some GreenCat's or Magniflow's. If done well I dont see why that would not be a viable option??? Harrop does have a tune for a decatted exhaust, unfortunately the current staff there don't seem to be very clued up, so I have lost a bit of faith in their advice. I would consider doing the rest of my exhaust also and will probably go for M3 world's x pipe and valved rear section. Any info or opinions would be appreciated. Cheers, Ash
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05-05-2020, 05:46 AM | #2 |
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https://afepower.com/afe-power-49-36...ith-resonators
that is what i have and it features a 300 cel primary catalyst. oem is 400 cel. it does not have secondary cats. the two sets of catalysts work together, so if you're environmentally conscious, i'm not sure just the 300 cel cats are going to ease your guilt. my car stinks a little bit, but i don't get a check engine light.
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05-08-2020, 11:28 PM | #4 | |
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Drives: 2011 M3 Coupe
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05-08-2020, 11:56 PM | #5 | ||
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He was old and didn't bend down last year. I might try it with just switching intakes back to oem and see if I can pull one over on him.
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05-09-2020, 01:20 AM | #7 | |||
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05-09-2020, 09:28 AM | #8 | ||||
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I coincidentally got a check engine light about 400 miles after I put this xpipe on. However, I think it was a coincidence. I didn't address it until I had to smog about a year later and the check engine light turned out to be an o2 sensor and a cold start component. One MAY have been related to the other. I've put over 500 miles on the car since I swapped back to this xpipe and Karbonius plenum (no tune) and no check engine light. I have to take my truck to a "star" station. I'm not sure if it is a more strict inspection, or a higher rated smog shop, but this f'n guy was crawling under my truck and pulling on hoses pretty hard. So I've seen it go both ways. The truck looks like shit and is not supposed to pass. I have to drive it 40 miles then I have a 20 mile window to get it smoged while the sensors show ready, but haven't tripped yet. Everything is there, it's just bad sensors or something.
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05-09-2020, 10:47 PM | #9 | |
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05-09-2020, 11:23 PM | #10 | ||
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I don't think I have any clips with the oem rear. Sounds fantastic with the vorsteiner. Just ok with the oem rear exhaust. Minimal rasp.
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05-10-2020, 12:49 AM | #11 |
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Do the AFE cats scrape? Most aftermarket cats in the primary location scrape since they are round and not pancake like OEM.
How much volume does the 300 cell + resonated midpipe add over stock? I’d love to squeeze any amount of power out of the midpipes but I haven’t yet since I have a super low tolerance for smell and noise. |
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05-10-2020, 12:51 AM | #12 | |||||
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05-10-2020, 03:47 AM | #13 |
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Scrippy- you said exactly what I was thinking. I am wondering about cutting the 400cell cats out and putting in some high flow green cats? If they fit? I am wondering if they will after some of the above comments.
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05-10-2020, 04:05 AM | #14 |
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can someone post a link to these "green cats?"
also scrip, if you're ever in orange county and want to take a quick ride, let me know.
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05-10-2020, 11:30 AM | #16 | ||||
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05-10-2020, 07:48 PM | #17 |
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the problem with the kooks greencats is their lack of information. does the width and length equate to in an oem car? zero information on their website.
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05-10-2020, 09:54 PM | #18 | |
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I wonder if these are the same (and cheaper). I am just buying some second hand AP racing breaks so I will have a look at how much space there is down there for a primary cat replacement. sounds like the external dimensions are 4"...
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05-10-2020, 10:15 PM | #19 | |
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05-10-2020, 10:17 PM | #20 |
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Haha, I know that. I was meaning while the car is in the air i can look at the exhaust
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cat, catalytic converter, e9x m3, exhaust, front exhaust, harrop, supercharger, up pipe |
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