09-22-2021, 11:08 AM | #1 |
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Sports cat on a stock exhaust?
Hi guys,
Just a quick one, my 435i N55 currently has a res delete and it’s going in for a sports cat to be fitted. The garage have told me the sound increase will be quite noticeable with this new sports cat fitted. Does anyone know how much increase I should expect sound wise? I do have a stock exhaust and a res delete. I don’t want too high expectations haha. Thanks in advance |
09-22-2021, 11:22 AM | #2 |
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I didn't delete my resonators but when i installed my high flow catted downpipe it was significantly louder. I didn't take any db readings or anything but there was absolutely no doubt that it was louder. That being said, without resonators you might find the sound to be a little tinny or ping-y with a high flow cat, just FYI. Some people like that though.
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09-22-2021, 11:27 AM | #3 |
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Lucky for you i have videos of all of this but not exactly in the order you did... I installed a fabspeed catted DP on completely stock exhaust (res + axleback), then later deleted the resonator. Most catted DPs don't change the volume significantly when you still have stock axleback, but you will get more turbo noise, a little more volume, rasp, and burble.
I personally like catted DP + res delete with stock axleback as it is tame enough to not drone or be excessively loud but still sounds good. |
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09-22-2021, 12:13 PM | #4 | |
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09-22-2021, 12:33 PM | #5 |
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09-22-2021, 12:34 PM | #6 |
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09-22-2021, 05:35 PM | #7 | ||
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09-23-2021, 12:01 PM | #9 |
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Usually the recommendations for nicer sounding exhaust (and louder):
1) Replace your down pipe first. and then if you want more... 2) Replace the muffler with a cat-back Usually the DP gives most people what they are looking for, but nothing beats the sound of a better exhaust. |
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09-23-2021, 12:28 PM | #10 | |
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The other important thing to remember is that DP adds performance and is a prerequisite for tunes whereas exhaust adds nothing for performance and is purely for sound. DP also affects emissions, exhaust does not. Also, a catback replaces the mid pipe and the muffler, whereas an axleback just replaces the muffler. For a N55 F3x, there is a single resonator in the midpipe, which will make a difference if you get a catback vs a axleback as some catbacks are non resonated. Another way to think about it is the effect each component post-turbo affects the exhaust volume. Of course, there is more than volume, there is drone, rasp, tone, etc. But volume is the easiest to quantify. So, think of it this way: Stock muffler reduces volume 50% Stock resonator reduces volume 20% Stock DP reduces volume 20%. Catted DP reduces 10% and catless 0%. So if 10/10 volume is catless DP and straight pipe (res and muffler delete), the OEM volume is 1/10 (and it is indeed very quiet). If you go catless with stock res/muffler, you are at 3/10, catted DP only 2/10. Res delete and catted DP you are at 4/10. This trend holds true with my own personal experience and all the videos and discussion i have seen with exhausts. Going from OEM DP to catted DP on my own car with completely stock exhaust only raised the volume a few dB. You almost couldnt tell unless you listen carefully. Of course, with res delete, it makes a bigger difference, since you have already removed another "muffler" from the system. Finally, its important to remember that the muffler has the Helmholtz chamber which is critical to reduce drone. So a muffler delete will have the single largest impact on drone. Last edited by thejeremyman9; 09-23-2021 at 12:38 PM.. |
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09-23-2021, 12:41 PM | #11 | |
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09-23-2021, 12:58 PM | #12 | |
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I think you will be pleased with the sound, the only question is if it will be "loud enough" for your taste. |
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09-23-2021, 01:14 PM | #13 | |
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09-23-2021, 01:58 PM | #14 | |
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09-23-2021, 02:35 PM | #15 | |
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09-24-2021, 11:15 AM | #16 |
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Update! Got it back today and boy it does sound a lot better than before! A sports cat and res delete combination I would recommend to any N55 owner. I think a muffler delete with this would be too much though as there is no drone currently
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09-24-2021, 01:46 PM | #17 |
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Same as my experience
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