12-05-2011, 12:49 PM | #1 |
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Restricted cat-back?
A well known N54 tuner has told me that an aftermarket cat-back exhaust will help the 1M gain top end power.
According to him, both the 135i and 1M share a restricted section of cat-back compared to the 335i and 535i. Typically, cat-back systems yield relatively minor power gains (though they often produce much nicer sounds). Has anybody compared the cat-back sections of 135i/1M relative to the 335i/535i? Thanks. Neil |
12-05-2011, 02:29 PM | #2 | |
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12-05-2011, 02:45 PM | #3 | |
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Thanks. Neil |
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12-05-2011, 02:46 PM | #4 | |
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http://www.1addicts.com/forums/showt...php?p=10917176 |
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12-05-2011, 02:51 PM | #5 | |
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12-05-2011, 02:56 PM | #6 | |
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The exhaust on the left which is the Berk does not have those. All it has are 2 small long resonators to make sure you don't get drone. Cats are extremely restrictive and resonator's aren't. |
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12-05-2011, 02:59 PM | #7 |
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It was unclear to me that Texas F1 --- and Cobb Tuning -- was referring to the secondary cats or some crimp in the tubing.
If the former (the cats), easy to address with an N55 or Berk Tech midpipe. Neil |
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12-05-2011, 06:30 PM | #8 |
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Neil, no, I'm not referring to the cats. What I was trying to describe earlier is what appears to be a restriction in the stock exhaust pipe immediately downstream from the flange where the cat-back portion connects to the secondary cat and resonator section. If you look at the diagram of the stock exhaust that Nate posted on the other thread, it's just past the dashed line that separates the portions of the system. It's hard to see from the diagram, but it is noticeable when you look at the actual pipe.
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12-05-2011, 07:56 PM | #9 | |
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Since the constriction is behind both the secondary cats and the resonator, it would be the rearmost section of the exhaust -- entailing the single pipe running to the muffler -- that would need to be replaced in order to "free-up" the system. Neil |
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12-06-2011, 10:02 AM | #10 | |
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